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Simultaneous measurement of the strain tensor of 10 individual grains embedded in an Al tensile sample
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
René V. Martins , Lawrence Margulies , Søren Schmidt , Henning F. Poulsen , Torben Leffers
Yıl :
2004
Materials Science and Engineering: A
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First results are presented on the simultaneous observation of the elastic strain tensor as a function of load of 10 individual grains, deeply embedded in the bulk of a polycrystalline Al tensile sample. The experimental technique is based on the use of focused high energy synchrotron radiation in transmission geometry. After each load step diffraction patterns are collected with a large-area X-ray detector system for a series of different angular and lateral sample positions. An automated indexing routine was used to assign sets of diffraction spots to individual grains. The strain tensor components as well as the individual grain position within the sample were then fitted from the diffraction spot positions. A maximum tensile load of 48 MPa was applied. Deviations in strain of up to 600 × 10−6 are observed between respective strain components of individual grains.
DOI : 10.1016/j.msea.2004.02.069
Anahtar Kelimeler : Stressu2013strain relationship measurements, X-ray diffraction, Synchrotron radiation
ISSN: 0921-5093
Cilt: 387-389
Sayfa: 84-88
Sınıflandırma :
2
Pseudoelasticity in an Fe–28Mn–6Si–5Cr shape memory alloy
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
Osamu Matsumura , Takashi Sumi , Naoya Tamura , Kenji Sakao , Takashi Furukawa , Hiroaki Otsuka
Yıl :
2000
Materials Science and Engineering: A
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Pseudoelasticity (PE) is clearly seen in Fe–28Mn–6Si–5Cr shape memory alloy exhibiting non-thermoelastic martensitic transformation, especially in the sheets hot rolled with a low finishing temperature (FT). Comparison between the temperature dependence of PE and that of shape memory effect (SME) indicates that the γ⇔ε transformation is responsible not only for the SME but also for the PE. As a result of consideration including variations in 0.2% proof stress and 2.0% flow stress with temperature, it is concluded that PE depends on the amount of the deformation due to the γ→ε transformation, the external stress and some temperature-dependent effects which balance against the ‘back stress’ on unloading. Effects of temperature and low-FT hot rolling on PE are discussed on the bases of the above-mentioned factors.
DOI : 10.1016/s0921-5093(99)00644-9
Anahtar Kelimeler : Pseudoelasticity, Shape memory effect, Martensitic transformation, ε Martensite, Feu2013Mnu2013Siu2013Cr alloy, Hot rolling temperature
ISSN: 0921-5093
Sayı: 1-2
Cilt: 279
Sayfa: 201-206
Sınıflandırma :
3
Two different types of deformation behaviors in ultrafine grained Mg alloys at high temperatures and development of the generalized constitutive equation for describing their deformation behavior
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
W.J. Kim , T.J. Lee
Yıl :
2014
Materials Science and Engineering: A
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The deformation behaviors of very fine-grained Mg–Al- and Mg–Zn-based alloys prepared by severe plastic deformation were examined, compared and analyzed over a wide range of temperatures between 448 K and 653 K at strain rates greater than 10−4 s−1 using strain rate change tests and elongation-to-failure tests. The two types of alloys exhibited different deformation behaviors in the relation between strain rate and stress. At low strain rates, the Mg–Al-based alloy exhibited characteristics of Coble creep, which became important as the temperature increased, whereas the Mg–Zn-based alloy exhibited threshold stress-like behavior associated with grain boundary sliding (GBS), which became obvious as the temperature increased. A constitutive equation was developed that can describe these different deformation behaviors in a single equation. In the equation, the threshold stresses for Coble creep and GBS, which are correlated to each other, were considered. According to the proposed equation, if the microstructure of ultrafine-grained Mg alloys is sufficiently thermally stable to retain small grain sizes, the achievement of high-strain-rate superplasticity controlled by Coble creep is possible. The most important factor that makes Coble creep important in Mg alloys compared with other metals was analyzed to be its relatively high grain boundary diffusion coefficient.
DOI : 10.1016/j.msea.2014.06.096
Anahtar Kelimeler : Mechanical characterization, Magnesium alloys, Thermomechanical processing, Grain refinement, Superplasticity
ISSN: 0921-5093
Cilt: 613
Sayfa: 264-273
Sınıflandırma :
4
Continuous flexible forming of three-dimensional surface parts using bendable rollers
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
Z.Q. Hu , M.Z. Li , Z.Y. Cai , X.P. Gong
Yıl :
2009
Materials Science and Engineering: A
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A novel idea to form three-dimensional (3D) sheet metal parts using three bendable rollers is presented. It can realize a continuous flexible forming of sheet metal. The forming principle is introduced and forming equipment with three bendable rollers has been developed. The bendable roller with shape-adjusting device is designed based on a flexible shaft of steel wires. Some experiments were performed and typical 3D surface parts were formed. The experiments show that the transversal spine of 3D part is determined by the bended shape of the bendable rollers, and the longitudinal spine of the 3D part is determined by the relative displacement among the top roller and the two bottom rollers. The technology of forming 3D surface sheet metal using bendable rollers can produce 3D surface parts in a rapid and economical way.
DOI : 10.1016/j.msea.2007.11.107
Anahtar Kelimeler : Continuous forming, Bending, Flexible forming, 3D surface sheet metal
ISSN: 0921-5093
Sayı: 1-2
Cilt: 499
Sayfa: 234-237
Sınıflandırma :
5
The dynamic response of the metastable β titanium alloy Ti-2Al-9.2Mo-2Fe at ambient temperature
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
J.F. Xiao , Z.H. Nie , C.W. Tan , G. Zhou , R. Chen , M.R. Li , X.D. Yu , X.C. Zhao , S.X. Hui , W.J. Ye , Y.T. Lee
Yıl :
2019
Materials Science and Engineering: A
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The mechanical behavior of a metastable β titanium alloy, Ti-2Al-9.2Mo-2Fe (wt%), was studied through high compression strain rate (~3000 s−1) at ambient temperature by Spilt Hopkinson Pressure Bar (SHPB) tests after solution treatment at 850 ℃ for 0.5 h and 950 ℃ for 1 h. The mechanism of deformation and microstructure evolution was investigated by electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). Multiple deformation mechanisms, including primary and secondary {332} twinning, stress-induced martensite, and stress-induced ω-phase and dislocation slips, were identified in specimens subjected to solution treatment at 850 ℃ for 0.5 h. In contrast, only primary and secondary {332} twinning and dislocation slips were detected in specimens subjected to solution treatment at 950 ℃ for 1 h. The athermal ω precipitation produced after solution treatment and elevated temperature generated during dynamic loading played a crucial role in the different deformation mechanisms observed in the two different specimens. Moreover, the deformation mechanisms active during plastic deformation in the different strain regimes affected the development of different textures in the Ti-2Al-9.2Mo-2Fe alloys from each regime.
DOI : 10.1016/j.msea.2019.02.068
Anahtar Kelimeler : Metastable β-titanium alloy, High strain rate, Deformation mechanism, Strain-hardening behavior
ISSN: 0921-5093
Cilt: 751
Sayfa: 191-200
Sınıflandırma :
6
Elastic and plastic characteristics of a model Cu–Zr amorphous alloy
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
Akiho Nakamura , Yasushi Kamimura , Keiichi Edagawa , Shin Takeuchi
Yıl :
2014
Materials Science and Engineering: A
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Athermal quasistatic simulation of shear deformation has been conducted for a realistic model Cu–Zr amorphous alloy to investigate characteristic features of elasticity and plasticity of the material. Significant reduction of the shear modulus by nonaffine atomic displacements and appreciable nonlinearity of elasticity have been observed. The fourth-order elastic constant in shear deformation and the ideal shear strength have been evaluated. Plastic deformation has been observed to start with isolated local shear transformations (LSTs) followed by collective LSTs leading to the formation of a shear band. Participation-ratio analysis (PRA) has demonstrated how the nonaffine displacement field converges as the system approaches the critical point of losing structural stability. PRA has also evaluated quantitatively the numbers of atoms participating in LSTs – the average number is about 30. Spatially anisotropic development of nascent shear band on a plane has been shown, attributable to anisotropic internal stress field induced by an LST. The evaluated stresses for the shear-band nucleation and for its propagation have indicated that the yielding in real materials is controlled by the shear-band propagation, as previously pointed out.
DOI : 10.1016/j.msea.2014.07.010
Anahtar Kelimeler : Amorphous alloy, Metallic glass, Elasticity, Plastic deformation, Computer simulation
ISSN: 0921-5093
Cilt: 614
Sayfa: 16-26
Sınıflandırma :
7
Effects of chemical composition, rolling and cooling conditions on the amount of martensite/austenite (M/A) constituent formation in low carbon bainitic steels
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
Shyi-Chin Wang , Jer-Ren Yang
Yıl :
1992
Materials Science and Engineering: A
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To understand the controlled-rolled granular bainite structure, a series of high-strength low-alloy steels was specially designed and investigated. The effects of the chemical composition, the finish-rolling temperature, and the cooling rate on the amount of martensite/austenite (M/A) constituent formation in the as-rolled alloy steels were evaluated. It was found that for steels containing the same addition of Nb (0.045 wt.%), the granular bainite transformation was retarded with an increased carbon content ranging from 0.021 to 0.056 wt.%. As the carbon content was raised, more niobium combined with carbon to form carbide, and the austenite therefore became niobium-depleted. This effect significantly influenced the granular bainite transformation for the steels studied. It is also shown that the effects of Mn and Mo on the formation of second phases are different from that of carbon. These alloying elements tend to promote the M/A constituent and depress pearlite formation. As to the effect of rolling temperature, it is shown that as the finish-rolling temperature is lowered, the larger strain accumulated in austenite enhances polygonal ferrite formation along the previous austenite grain boundaries, and reduces the amount of M/A constituent. Furthermore, based on a thermodynamic analysis, it is indicated that the granular bainite transformation terminates as the carbon content of austenite reaches the TO curve. The critical carbon content increases with the decrease of the granular bainite transformation temperature. It was also found that the amount of M/A constituent formation decreases with the increase in cooling rate. This result is not consistent with that reported by Shiga et al., Tetsu-to-Hagane, 68 (1982) A227 and Bufalini et al., Accelerated cooling of steel,
DOI : 10.1016/0921-5093(92)90361-4
ISSN: 0921-5093
Sayı: 1
Cilt: 154
Sayfa: 43-49
Sınıflandırma :
8
On the nonlinear elastic properties of textile reinforced concrete under tensile loading including damage and cracking
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
Mike Richter , Bernd W. Zastrau
Yıl :
2006
Materials Science and Engineering: A
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This paper is focussed on the description of the macroscopic nonlinear elastic material behaviour of textile reinforced concrete (TRC) using an analytical approach. Damage and cracking of the composite are considered as well. The heterogeneous structure of TRC is modelled on the mesoscopic level and the overall material behaviour on the macroscopic level is obtained by means of homogenisation. The analytical approach is based on the micro-mechanical solution for a single inclusion according to Eshelby. In extension of this solution for multi-directionally reinforced concrete an effective field approximation is used. This approach allows the consideration of the interactions between the differently orientated rovings and also between rovings and micro-cracks in an average sense. The micro-cracks are included in the mechanical model by using a micro-crack density parameter. For the mechanical modelling of the bond behaviour between roving and matrix after the initiation of macro-cracking a slip-based bond model with a multiple linear shear stress–slip relation is introduced.
DOI : 10.1016/j.msea.2006.02.007
Anahtar Kelimeler : Textile reinforced concrete, Homogenisation, Effective field approximation, Micro-crack density parameter, Slip-based bond model
ISSN: 0921-5093
Sayı: 1-2
Cilt: 422
Sayfa: 278-284
Sınıflandırma :
9
The effect of processing parameters on the flexural properties of unidirectional carbon fibre-reinforced polymer (CFRP) composites
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yıl :
2008
Materials Science and Engineering: A
Yayıncı Web Sitesi
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The flexural properties (e.g., strength, elastic modulus) of unidirectional carbon fibre-reinforced polymer matrix composites were optimised by controlling the following processing parameters during manufacture: (i) concentration of epoxy (45–65 wt.%) within an acetone solution for wetting the carbon fibres, (ii) compressive pressure (0.25–1.25 MPa), and (iii) holding time (20–40 min) applied during vacuum autoclave curing at 120 °C. Flexural properties of the resulting composites were evaluated using the three-point bend configuration in accordance with the ASTM D790-03 standard. Overall it was concluded that optimum flexural properties (e.g., 1292 MPa flexural strength) were achieved using a 50 wt.% epoxy solution, 1.0 MPa compressive pressure, and 30 min holding time during vacuum autoclave curing.
DOI : 10.1016/j.msea.2007.11.148
Anahtar Kelimeler : Composite, CFRP, Carbon fibre, Processing Conditions, Flexural properties, Mechanical
ISSN: 0921-5093
Sayı: 1-2
Cilt: 498
Sayfa: 65-68
Sınıflandırma :
10
Microstructure and texture evolution of Mg3Zn3Ce magnesium alloys sheets and associated restoration mechanisms during annealing
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
M. Sanjari , S.F. Farzadfar , T. Sakai , H. Utsunomiya , E. Essadiqi , In-Ho Jung , S. Yue
Yıl :
2013
Materials Science and Engineering: A
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Kaydet Alıntıla
The texture evolution in four Mg3Zn3Ce alloys was compared to that of Mg33Al31Zn (AZ31) alloy following rolling and subsequent isothermal annealing. All the as-cast and homogenized alloys were rolled through two stages that can be characterized as rough rolling and finish rolling, respectively. To investigate the effect of finish rolling temperature, one finish rolling pass with 65% reduction in thickness was performed at 300 °C and 450 °C. Of the studied compositions, the Mg31Zn31Ce, which had the highest Ce/Zn ratio, showed the weakest as-rolled texture and homogenous shear banding/twinning. Changing the Zn content changed particle size and, in alloys subject to texture weakening, the static recrystallization mechanism altered. On annealing, the maximum intensity of basal pole figures decreases as recrystallization progresses. The Mg31Zn31Ce (with the highest Ce/Zn), texture weakening is maintained even after full recrystallization, when grain coarsening occurs. However, in the Mg34Zn31Ce and AZ31 alloys, texture strengthening occurs when grain coarsening occurs, and the double split basal peak is replaced by a single peak. In these two alloys, grain coarsening is also accompanied by a bimodal grain size whereas in the Mg31Zn31Ce alloy, the grain coarsening leads to a uniform grain size. It is concluded that the differences between the Ce bearing alloys are related to Zn; increasing Zn decreases the solubility of Ce, which can influence the texture changes.
DOI : 10.1016/j.msea.2012.10.075
Anahtar Kelimeler : Magnesium alloys, Rare-earth, Recrystallization, Texture
ISSN: 0921-5093
Cilt: 561
Sayfa: 191-202
Sınıflandırma :
11
Ni–Mn–Ga high-temperature shape memory alloys
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
H.B. Xu , Y. Li , C.B. Jiang
Yıl :
2006
Materials Science and Engineering: A
Yayıncı Web Sitesi
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Kaydet Alıntıla
The relationship among the composition, structure and martensitic transformation temperatures have been studied in detail for Ni50−xMn25Ga25−x (at.%) alloys by optical and transmission election microscopy, X-ray diffraction and differential scanning calorimeter measurements. The martensitic transformation temperatures almost linearly increase with increasing Ni content up to 670 K showing their potentials as high-temperature shape memory alloys. The results show that the tetragonality ratio (c/a) increases with the Ni substitution for Ga, but the unit-cell volume reduces simultaneously. The martensitic transformation characteristics of Ni54Mn25Ga21 alloy with single martensite phase show excellent stability during thermal cycles or aging. The polycrystalline Ni54Mn25Ga21 alloy exhibited a shape-memory effect of 4.2% and compressive strain larger than 10% by using grain refining technique. Addition of Fe as a fourth element is an effective method to improve the mechanical properties, especially plasticity of polycrystalline Ni–Mn–Ga alloy due to the precipitation of γ-phase. A compressive strain of 30% and a shape-memory effect of 2.8% are obtained for Ni56Mn17Fe8Ga19 alloy.
DOI : 10.1016/j.msea.2006.02.187
Anahtar Kelimeler : NiMnGa, Shape memory alloy, Martensitic transformation, Grain refinement, Fe alloying
ISSN: 0921-5093
Cilt: 438-440
Sayfa: 1065-1070
Sınıflandırma :
12
Influence of argon gas bubbles and non-metallic inclusions on the flow behavior in steel continuous casting
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
C. Pfeiler , M. Wu , A. Ludwig
Yıl :
2005
Materials Science and Engineering: A
Yayıncı Web Sitesi
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The present study uses an Eulerian–Lagrangian approach to model the 3D turbulence (k–ɛ) flow of the steel melt (continuous phase) and the trajectories of individual non-metallic inclusions and gas bubbles (dispersed phase) in a continuous casting. The dispersed phase is considered as numerous mass-loaded particles with different classes of diameters and densities. To consider the interaction between the continuous and the dispersed phases two different methods are studied and compared. The first method, i.e. the one-way coupling, considers only the impact of the melt flow on the trajectories of the dispersed phases, while the influence of the dispersed phases on the melt flow is ignored. With the second method, namely the two-way coupling, both bidirectional influences are considered. The presented results indicate that coupling the bidirectional interactions is essential to get realistic results, especially in the presence of large gas bubbles.
DOI : 10.1016/j.msea.2005.08.178
Anahtar Kelimeler : Turbulence, Continuous casting, Submerged entry nozzle, Inclusion, Bubble, Dispersed phase
ISSN: 0921-5093
Cilt: 413-414
Sayfa: 115-120
Sınıflandırma :
13
Effect of ball milling on microstructure and mechanical properties of 6061Al matrix composites reinforced with high-entropy alloy particles
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
Weiping Chen , Zixuan Li , Tiwen Lu , Tianbing He , Ruikai Li , Bing Li , Bingbing Wan , Zhiqiang Fu , Sergio Scudino
Yıl :
2019
Materials Science and Engineering: A
Yayıncı Web Sitesi
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Kaydet Alıntıla
6061Al matrix composites reinforced by 7.5 vol.% nanocrystalline CoNiFeAl0.4Ti0.6Cr0.5 high-entropy alloy (HEA) particles have been synthesized by powder processing of powder mixture ball milled for 10 h, 20 h and 40 h. Results indicated that the average ultimate tensile strength and fracture strain of the 6061Al-HEA-10 h composite were 378 MPa and 8.4%, better than those of the 6061Al-HEA-20 h composite, which was related to the homogeneous distribution of HEA particles. Specifically, the 6061Al-HEA-40 h composite had the highest ultimate strength and yield strength, and the fracture strain was close to the 6061Al-HEA-20 h composite, related with the formation of fine HEA particle clusters and a heterogeneous grain structure. The strengthening mechanisms for the improved strength of the composites are mainly derived from the Hall–Petch effect and geometrically necessary dislocations.
DOI : 10.1016/j.msea.2019.138116
Anahtar Kelimeler : Metal matrix composites, High-entropy alloy reinforcement, Milling time, Heterogeneous structure, Mechanical properties
ISSN: 0921-5093
Cilt: 762
Sayfa: 138116
Sınıflandırma :
14
Microstructure anisotropy and its implication in mechanical properties of biomedical titanium alloy processed by electron beam melting
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
M. Wang , H.Q. Li , D.J. Lou , C.X. Qin , J. Jiang , X.Y. Fang , Y.B. Guo
Yıl :
2019
Materials Science and Engineering: A
Yayıncı Web Sitesi
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Titanium alloy Ti-6Al-4V processed by electron beam melting (EBM) has a great potential for orthopedic and aerospace applications. However, the process induced porosity and microstructure anisotropy will have a significant impact on the material properties. This work has found that spherical and elongated pores with strong size effect are common characteristics for the as-EBM samples made with horizontal, diagonal, and vertical orientations w.r.t. the substrate. Furthermore, the major axis of the elongated pores is perpendicular to build direction for samples with different build orientations. The microstructure consists of columnar prior β grains delineated by grain boundary α and transformed α/β structures with α’ marteniste and basket weave morphology. Of note is that a high fraction of twin boundaries are prevalent in α (α’) phase. The configuration of the applied load w.r.t. the major axis of the elongated pores is the most significant influencing factor to mechanical properties, while the columnar prior β grain structure is secondary. Fractography reveals that microcracks tend to originate from elongated pores for cleavage fracture. In addition, the co-existing local terrace-like and shallow dimples are attributed to the intergranular crack propagation from the lamella α grain boundaries. Thus, the anisotropy of porosity and microstructure is of significance to enhance mechanical properties in process development.
DOI : 10.1016/j.msea.2018.11.038
Anahtar Kelimeler : Electron beam melting, Microstructure anisotropy, Mechanical property, Titanium alloy, Additive manufacturing
ISSN: 0921-5093
Cilt: 743
Sayfa: 123-137
Sınıflandırma :
15
Experiments and modeling of spark plasma sintered, functionally graded boron carbide–aluminum composites
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
Dustin M. Hulbert , Dongtao Jiang , Umberto Anselmi-Tamburini , Cosan Unuvar , Amiya K. Mukherjee
Yıl :
2008
Materials Science and Engineering: A
Yayıncı Web Sitesi
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Continuous functionally graded boron carbide aluminum cermets were created using spark plasma sintering. The B4C compacts with large, precipitous density gradients were melt infiltrated with 99.999% Al at 1453 K for 10 min. The microstructure of the material exhibits a gradual change from fully dense B4C with a nominal grain size of 2 μm and a hardness of 32.3 GPa to a B4C–Al cermet with a B4C grain size on the order of 200 nm and a hardness of 8.36 GPa. Prior to melt infiltration, X-ray diffraction data indicates that the B4C compacts have some microstructural defects present. This result is confirmed by the presence of twins on the fully dense fracture surface. Following melt infiltration, X-ray diffraction reveals that some of the defects are dissipated and small amounts of Al3BC are present. Numerical modeling results indicate the presence of a 405 K temperature difference between the top and bottom of a specimen using this method and help confirm experimental observations.
DOI : 10.1016/j.msea.2007.11.054
Anahtar Kelimeler : Functionally graded materials, Spark plasma sintering, Boron carbide, Aluminum, Composites
ISSN: 0921-5093
Sayı: 1-2
Cilt: 488
Sayfa: 333-338
Sınıflandırma :
16
High temperature tensile properties of a series of nickel-base superalloys on a γ/γ′ tie line
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
Y. Ro , Y. Koizumi , H. Harada
Yıl :
1997
Materials Science and Engineering: A
Yayıncı Web Sitesi
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Kaydet Alıntıla
A series of nickel-base superalloys with γ′ fractions changed from 0 to 100 mol% and with γ and γ′ compositions kept constant were designed and examined in terms of high temperature tensile properties. In the temperature range from 900 to 1000°C, 0.2% proof stress shows a maximum at about 85 mol% in a corrected amount of γ′, whereas at 1100°C, it shows maximum at about 65 mol%. The maximum shift of proof stress from the law of mixture in strength was constant for these temperatures. In the strain rate range from 10−8 to 10−2/s at 1000°C, the maximum shift of proof stress increased with the strain rate. The proportion of the shift stress to the proof stress becomes larger as the temperature increases.
DOI : 10.1016/s0921-5093(96)10504-9
Anahtar Kelimeler : Nickel-base superalloys, γ/γu2032, High temperature, Proof stress
ISSN: 0921-5093
Sayı: 1-2
Cilt: 223
Sayfa: 59-63
Sınıflandırma :
17
Dimensional behaviour of aluminium sintered in different atmospheres
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
T. Pieczonka , Th. Schubert , S. Baunack , B. Kieback
Yıl :
2008
Materials Science and Engineering: A
Yayıncı Web Sitesi
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Kaydet Alıntıla
The sinterability of pure aluminium powder was controlled in different sintering atmospheres, i.e. nitrogen, argon, nitrogen/hydrogen and nitrogen/argon gas mixtures, and also in vacuum. Dimensional changes occurring during sintering were monitored by dilatometry. Thermogravimetric analysis (TG) was used to recognize possible interactions between aluminium and nitrogen. Pure nitrogen was found to be the only active sintering atmosphere for aluminium, promoting shrinkage, associated with a weight gain by binding nitrogen, and enhancing mechanical properties of the sintered compacts. Hydrogen lowers the sinterability of aluminium very strongly, even when present in small concentrations in a nitrogen atmosphere. Auger electron spectroscopy was used to characterize the surface layers on aluminium powder particles, fractured green compacts and sintered samples. Distributions of aluminium, nitrogen, oxygen and other elements, contained as impurities, were obtained by depth profiling measurements on this surfaces. Indications are that enhanced concentration of magnesium within the powder particle surface film promotes sintering of aluminium.
DOI : 10.1016/j.msea.2007.06.002
Anahtar Kelimeler : Sintering of aluminium, Sintering atmosphere, Dilatometry, AES
ISSN: 0921-5093
Sayı: 1-2
Cilt: 478
Sayfa: 251-256
Sınıflandırma :
18
Achieving high uniformity of the elastic strain energy accumulation rate during the serrated plastic flows of bulk metallic glasses
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
H.H. Tang , Y.C. Cai , Q. Zuo , S.H. Chen , R.P. Liu
Yıl :
2018
Materials Science and Engineering: A
Yayıncı Web Sitesi
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Kaydet Alıntıla
The shear-band formation and propagation mechanisms of bulk metallic glasses (BMGs) have been studied extensively, however, the interpreting of the mechanisms of the serrated plastic flows is still challenging. In this work, the variation of the elastic strain energy accumulation rates of the serrations during the plastic flows of BMGs was examined using a statistical analysis. High uniformity of elastic strain energy accumulation rates was achieved in the serrated plastic flows under complex stress fields with three-parameter Weibull modulus reaching to 14.29, which is much larger than the value of 4.06 under conventional compression tests. The variations of the elastic strain energy accumulation rates are related to the formation and propagation of shear bands under varying loading conditions, and the high uniformity under complex stress fields is due to that the formation and propagation of shear bands can be confined to certain shearing path. The present findings are of significance for giving more insight into the mechanisms of the serrated plastic flows of BMGs.
DOI : 10.1016/j.msea.2018.09.003
Anahtar Kelimeler : Bulk metallic glass, Statistics analysis, Serrated plastic flow, Elastic strain energy accumulation rate
ISSN: 0921-5093
Cilt: 736
Sayfa: 269-275
Sınıflandırma :
19
Atomic structure of grown-in antiphase boundaries (APB2) in the Fe-28Al-5Cr (at.%) alloy
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
M. Karlik
Yıl :
1997
Materials Science and Engineering: A
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
Thermal grown-in antiphase boundaries (APBs) of the next-nearest neighbour (APB2) type in the Fe-28Al-5Cr (at.%) alloy were studied in the edge-on orientation by means of high resolution electron microscopy. The interfaces are thin and sharp. The domain walls are rugged, small facets (ledges) 0.5–5 nm long situated in the (100) and (111) planes were observed. Two different structures of the APB2 interface with opposite fault vectors were found. Their atomic arrangements are interpreted by contrast simulations, using two models of stacking of the Al and Fe planes in the boundary.
DOI : 10.1016/s0921-5093(97)00160-3
Anahtar Kelimeler : Iron-aluminium alloys (based on Fe3Al), Antiphase domains, High resolution electron microscopy
ISSN: 0921-5093
Cilt: 234-236
Sayfa: 212-215
Sınıflandırma :
20
Microstructure refinement and its effect on properties of spring steel
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
B. Podgornik , V. Leskovšek , M. Godec , B. Senčič
Yıl :
2014
Materials Science and Engineering: A
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
Over the last decades considerable efforts have been made to develop high performance spring steels, which would allow vehicles weight reduction. One way of improving steel properties is by refining its microstructure and reducing the amount of inclusions. Therefore, the aim of the current investigation was to determine the effect of cleaner and more uniform microstructure obtained through electro-slag remelting (ESR) on the mechanical and dynamic properties of spring steel. Investigation was performed on hot rolled, soft annealed and vacuum heat treated 51CrV4 spring steel produced by conventional continuous casting and refined through ESR. Effect of microstructure refinement was evaluated in terms of tensile strength, elongation, fracture and impact toughness, and fatigue resistance under bending and tensile loading. Results show that although ESR gives some improvement, especially in terms of better repeatability and reduced scattering, it has a negative effect on the fatigue properties of spring steel.
DOI : 10.1016/j.msea.2014.01.054
Anahtar Kelimeler : Spring steel, Electro-slag remelting, Microstructure refinement, Mechanical characterization, Fracture toughness, Fatigue
ISSN: 0921-5093
Cilt: 599
Sayfa: 81-86
Sınıflandırma :
21
Author Index
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yıl :
2015
Materials Science and Engineering: A
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
DOI : 10.1016/s0921-5093(15)00079-9
ISSN: 0921-5093
Cilt: 626
Sayfa: 514-516
Sınıflandırma :
22
Development and evaluation of TiAl sheet structures for hypersonic applications
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
S.L. Draper , D. Krause , B. Lerch , I.E. Locci , B. Doehnert , R. Nigam , G. Das , P. Sickles , B. Tabernig , N. Reger , K. Rissbacher
Yıl :
2007
Materials Science and Engineering: A
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
A cooperative program between the National Aeronautics and Space Administration (NASA), the Austrian Space Agency (ASA), Pratt & Whitney, Engineering Evaluation and Design, and Plansee AG was undertaken to determine the feasibility of achieving significant weight reduction of hypersonic propulsion system structures through the utilization of TiAl. A trade study defined the weight reduction potential of TiAl technologies as 25–35% compared to the baseline Ni-base superalloy for a stiffener structure in an inlet, combustor, and nozzle section of a hypersonic scramjet engine. A scramjet engine inlet cowl flap was designed, along with a representative subelement, using design practices unique to TiAl. A subelement was fabricated and tested to assess fabricability and structural performance and validate the design system. The TiAl alloy selected was PLANSEE's third generation alloy Gamma Met PX,1 a high temperature, high-strength γ-TiAl alloy with high Nb content. Characterization of Gamma Met PX sheet, including tensile, creep, and fatigue testing was performed. Additionally, design-specific coupons were fabricated and tested in order to improve subelement test predictions. Based on the sheet characterization and results of the coupon tests, the subelement failure location and failure load were accurately predicted.
DOI : 10.1016/j.msea.2007.02.020
Anahtar Kelimeler : Titanium aluminide, Sheet, Mechanical properties, Fabrication
ISSN: 0921-5093
Sayı: 1-2
Cilt: 464
Sayfa: 330-342
Sınıflandırma :
23
High temperature thermo-mechanical and low cycle fatigue behaviors of DD32 single crystal superalloy
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
Jinjiang Yu , Guoming Han , Zhaokuang Chu , Xiaofeng Sun , Tao Jin , Zhuangqi Hu
Yıl :
2014
Materials Science and Engineering: A
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
Fatigue cycles decrease in the sequence of in-phase TMF (IP), isothermal low cycle fatigue (IF), out-of-phase TMF (OP) in the temperature ranges from 600 °C to 900 °C when the total strain amplitude is taken as the basis. However, fatigue life decreases in the sequence of IF, OP, and IP with the mechanical strain range as the basis. At lower strain amplitude, the fracture surfaces of OP present a mass of typical fatigue steps. Nevertheless, at higher strain amplitude in IP case the fracture surfaces with a lot of planar dimples are similar to those of high temperature creep test. The common deformation features of IP, OP, and IF are a network of dislocations at lower strains and well defined dislocation bands at higher strains.
DOI : 10.1016/j.msea.2013.10.055
Anahtar Kelimeler : Single crystal superalloy, Thermo-mechanical fatigue, Deformation mechanism
ISSN: 0921-5093
Cilt: 592
Sayfa: 164-172
Sınıflandırma :
24
Novel NiAl-strengthened high entropy alloys with balanced tensile strength and ductility
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
Haoyan Diao , Dong Ma , Rui Feng , Tingkun Liu , Chao Pu , Chuan Zhang , Wei Guo , Jonathan D. Poplawsky , Yanfei Gao , Peter K. Liaw
Yıl :
2019
Materials Science and Engineering: A
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
A single phase, face-centered-cubic (FCC) Al0.3CoCrFeNi high entropy alloy usually has low yield strength. Here, a precipitate-strengthened Al0.3CoCrFeNi has been developed, exhibiting enhanced yield strength while retaining good ductility, which is attributed to a novel microstructure comprising a finely distributed, needle-like B2 phase within the grains of the FCC matrix and a granular σ phase along the grain boundaries. Such a microstructure was obtained by a two-step heat treatment of an as-cast Al0.3CoCrFeNi, whose parameters were determined by integrating CALPHAD-based thermodynamic calculations with microstructural characterization by atom probe tomography. In situ neutron diffraction, in conjunction with crystal-plasticity finite-element simulations, has revealed the strengthening effect owing to the load partitioning between the constituent phases. This work has important implications for understanding phase stability and deformation mechanisms in multi-principal component alloys, and paves the way for developing novel microstructures in complex alloys using correlative techniques.
DOI : 10.1016/j.msea.2018.11.055
Anahtar Kelimeler : High entropy alloys, Tensile strength, Atom probe tomography, In situ neutron diffraction, Thermodynamic calculations
ISSN: 0921-5093
Cilt: 742
Sayfa: 636-647
Sınıflandırma :
25
Long-term bending creep behavior prediction of injection molded composite using stress–time correspondence principle
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
Mohamed Hadid , Said Rechak , Abdelouahab Tati
Yıl :
2004
Materials Science and Engineering: A
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
In analogous manner to the time–temperature superposition principle, the stress–time superposition principle approach is used to predict long-term material creep behavior without extensive laboratory test time. The bending creep of the injection fiber glass reinforced polyamide is studied. An improved empirical model is used to construct the creep master curve, to take into account the strong non-linear behavior. An excellent superposition of curves is obtained and, in a long-term, an important curvature in the master curve is registered.
DOI : 10.1016/j.msea.2004.04.023
Anahtar Kelimeler : Viscoelasticity, Creep, Bending, Superposition, Polyamide, Composite
ISSN: 0921-5093
Sayı: 1-2
Cilt: 385
Sayfa: 54-58
Sınıflandırma :
26
The correlation between the flow behavior and the microstructure evolution during hot working of TC18 alloy
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
J. Luo , L.F. Wang , S.F. Liu , M.Q. Li
Yıl :
2016
Materials Science and Engineering: A
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
The effects of processing parameters on the flow stress, the strain rate sensitivity and the strain hardening exponent of TC18 alloy are investigated in present study. The isothermal compression is performed in the deformation temperature range of 993–1203 K, strain rate range of 0.01–5.0 s−1 and strain range of 0.5–1.2. The micro-mechanisms that might control flow behavior are analyzed using optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results demonstrate that the shapes of flow curves are dependent on the competing processes of the work-hardening, the thermal softening and the microstructure-related softening. The maximum m-value of 0.45 occurs at a deformation temperature of 993 K, a strain rate of 0.01 s−1 and a strain of 0.5. At 0.1 s−1, the m-value is approximately 0.20–0.27, implying that controlling deformation mechanism is dislocation glide/climb. At a deformation temperature of 1053 K and a strain of 0.5, the levels of n-value decrease from 0.01 s−1 and 1.0 s−1, respectively, to 0.1 s−1. The more significant softening effect at 0.1 s−1 is attributed to the medium thermal softening and the microstructure-related softening.
DOI : 10.1016/j.msea.2015.12.040
Anahtar Kelimeler : TC18 alloy, Strain rate sensitivity, Strain hardening exponent, Dynamic recovery, Dynamic recrystallization
ISSN: 0921-5093
Cilt: 654
Sayfa: 213-220
Sınıflandırma :
27
A relation between a metallic film covering on diamond and diamond nucleation and growth at high-temperature–high-pressure in a Ni–Mn–C system
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
Bin Xu , Mu-sen Li , Li Li , Ai-min Xu , Yu-chao Niu
Yıl :
2007
Materials Science and Engineering: A
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
There exists a thin metallic film covering on a growing diamond during diamond synthesis at high-pressure and high-temperature (HPHT). Through the film the graphite carbon is catalyzed into diamond structure and transferred to the surface of growing diamond. Study on the chemical composition and structure of the metallic film is of great importance to study the diamond nucleation and growth mechanism and to prepare high-quality single-crystalline diamond. In this paper, a thin metallic film covering on diamond crystals grown from a Ni–Mn–C system was investigated by scanning Raman spectroscopy, scanning auger microprobe, electron probe microanalysis and transmission electron microscopy. It was found that diamond structure was not found in the film, the state of carbon atoms does not significantly change and the fine structures of carbon atoms almost do not transform within the whole metallic film. However, diamond structure was observed on the surface of the film contacting directly with the as-grown diamond, while crystalline graphite and amorphous carbon were not found on the surface. Based on the systemic study of microstructures on the metallic film, it could be reasonably suggested that graphite could not be directly catalyzed into diamond structure in the molten film at HPHT, and the diamond formation should be finished on the diamond–film interface.
DOI : 10.1016/j.msea.2006.11.014
Anahtar Kelimeler : High-temperature and high-pressure, Diamond, Graphite, Thin metal film covering on diamond
ISSN: 0921-5093
Cilt: 454-455
Sayfa: 293-299
Sınıflandırma :
28
Surface nanocrystallization of Cu and Ta by sliding friction
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
Y.S. Zhang , P.X. Zhang , H.Z. Niu , C. Chen , G. Wang , D.H. Xiao , X.H. Chen , Z.T. Yu , S.B. Yuan , X.F. Bai
Yıl :
2014
Materials Science and Engineering: A
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
Optimization of the surface structure and properties is of great concern since the failures of engineering materials such as wear, erosion and fatigue usually occur on the surface of materials. Plastic deformation from the sliding friction process has been utilized to realize surface nanocrystallization in commercial pure copper and tantalum plates in this work. The optical microscopy, transmission electron microscopy, X-ray photoelectron spectra, and uniaxial tensile testing results suggested that clean nanocrystalline surface layers of pure copper and tantalum were obtained, significantly strengthening the materials after the treatment.
DOI : 10.1016/j.msea.2014.03.089
Anahtar Kelimeler : Nanostructured materials, Non-ferrous alloys, Grain refinement
ISSN: 0921-5093
Cilt: 607
Sayfa: 351-355
Sınıflandırma :
29
Mechanical property and characterization of a NiCoCrAlY type metallic bond coat used in turbine blade
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
Ashok Kumar Ray , Nilima Roy , Abhijit Kar , Ajoy Kumar Ray , Samir Chandra Bose , Gautam Das , Jitendra Kumar Sahu , Dipak Kumar Das , B. Venkataraman , Srikanth V. Joshi
Yıl :
2009
Materials Science and Engineering: A
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
This paper highlights some of the results obtained while studying Ni20Co18Cr12.5Al0.6Y (NiCoCrAlY) type metallic bond-coat properties of a thermal-barrier coated (TBC), AE-437A Ni base superalloy mostly employed for manufacturing compressor and stationary stator blades in aero turbines. Experiments were mainly focused in the area of evaluation of microstructure, residual stress, shear strength, hardness and with special emphasis in establishing the ductile to brittle transition temperature (DBTT) of the bond coat by using acoustic emission technique during room temperature and high temperature tensile tests. Results reveal that the residual stress was tensile in nature in the TBC layer and compressive in the bond coat as well as in the substrate. The DBTT of this bond coat is around 650 °C, which is in close proximity to the value reported in literature for CoCrAlY type of bond coat. Finite element technique was used to analyze the equivalent stresses in the bond coat, the result of which revealed the highest order of equivalent stress 800 °C, as the bond coat is ductile above 650 °C. Shear strength of the bond coat is in close proximity with that of the bond strength reported in literature for CoCrAlY and Ni22Co17Cr12.5Al0.6Y types of bond coat.
DOI : 10.1016/j.msea.2008.11.066
Anahtar Kelimeler : Thermal-barrier coating, Bond coat, Mechanical strength, Acoustic emission, Residual stress
ISSN: 0921-5093
Sayı: 1-2
Cilt: 505
Sayfa: 96-104
Sınıflandırma :
30
Precipitation in Al–Cu–Mg alloy during creep exposure
Dergi Makalesi

Dergi Makalesi
Kaynak :
Science Direct
Dergi:
Materials Science and Engineering: A
Yayıncı:
Elsevier
Yazar(lar) :
Y.C. Lin , Yu-Chi Xia , Yu-Qiang Jiang , Lei-Ting Li
Yıl :
2012
Materials Science and Engineering: A
Yayıncı Web Sitesi
Tam Metin
Kaydet Alıntıla
The uniaxial tensile creep tests of Al–Cu–Mg alloy were carried out over a wide range of temperature and applied stress. The effects of applied stress and creep aging temperature on the precipitation in Al–Cu–Mg alloy were discussed. It is found that the precipitation process is very sensitive to the applied stress and creep aging temperature, and S phase (CuMgAl2) is the main precipitate under the tested creep conditions. With the increase of applied stress and creep aging temperature, S phase easily grows up and becomes sparse. Meanwhile, the creep aging leads to the discontinuous distribution of precipitation phase in grain boundary, which can improve the corrosion-resistance of Al–Cu–Mg alloy. Because the lattice misfit of acicular exudation phase is far less than that of disk-shaped phase, the applied stress/strain fields will alert the competitive precipitation equilibrium between different strengthening phases. So, the large applied stress and high aging temperature easily make the preferential precipitation process as SSS→GPB→S″→S′→S.
DOI : 10.1016/j.msea.2012.07.069
Anahtar Kelimeler : Aluminum alloy, Aging, Precipitation
ISSN: 0921-5093
Cilt: 556
Sayfa: 796-800
Sınıflandırma :

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