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991.
Yolanda HedbergOskar Karlsson Peter SzakalosInger Odnevall Wallinder 《Materials Letters》2011,65(14):2089-2092
Electron Backscatter Diffraction (EBSD) studies clearly revealed a different crystallographic structure of the smallest particle size fraction of gas-atomized AISI 316 L stainless steel powder (< 4 μm) compared with larger sized fractions of the same powder (< 45 μm). Despite similar chemical compositions, the predominating structure of the smallest particle size fraction was ferritic (i.e., has ferromagnetic properties) whereas the larger sized particle fractions and massive 316 L revealed an expected austenitic and non-magnetic structure. From these findings, it follows that direct magnetic separation can be applied to separate very fine sized particles. These structural differences explain previously observed dissimilarities from corrosion and metal release perspectives. 相似文献
992.
A. Ananthanarayanan G.P. Kothiyal L. Montagne G. Tricot B. Revel 《Materials Chemistry and Physics》2011
The effect of P2O5 incorporation on the sintering, flow and crystallization characteristics of BCABS glasses of composition (mol%) 35BaO–15CaO–5Al2O3–(37 − x)SiO2–8B2O3–xP2O5 (0 ≤ x ≤5) is investigated. It is observed that addition of P2O5, removes cations (Ba2+ and Ca2+) from the silicate network, resulting in an increase in polymerization. This is reflected by a reduction in TEC and an increase in sealing temperature. In addition, the removal of cations for charge compensation causes a change in major crystalline phases formed, from BaSiO3 to Ba(Al2Si2O8). In addition, beyond 3 mol% P2O5, crystallization of phosphate phases is evident. Based upon the flow temperature, glasses with 0, 1 and 2 mol% P2O5 are selected for sealing. In these glasses, conversion of Cr to Cr2O3 is observed, yielding improved adhesion. However, the 2 mol% P2O5 glass showed an increased crystallization tendency, resulting in incomplete sintering. Therefore, 1 mol% P2O5 seems a good compromise for sealing with improved adhesion. 相似文献
993.
Dragica M. Minić Vladimir A. Blagojević Dušan M. Minić Tomáš Žák 《Materials Chemistry and Physics》2011
As a result of the preparation process of Fe81Si4B13C2 amorphous alloy ribbon, a difference has been observed between the opposite sides of the ribbon in microstructure and surface morphology. Influence of these differences on thermally induced structural transformations was studied. Thermal treatment below 600 °C had a significant influence on the evolution of the microstructure, as well as phase composition of individual sides of the ribbon. Treatment at higher temperatures caused the microstructural differences between two sides to decrease significantly. Phase composition of the alloy samples showed the opposite trend: the differences observed were the greatest in the fully crystallized alloy, after treatment at 700 °C. These differences are the result of different numbers of nucleation sites for Fe2B phase on respective sides of the ribbon, leading to 30% difference in its content on different sides in the fully crystallized alloy. 相似文献
994.
The effects of the addition of Zn element on the microstructures, mechanical properties and bio-corrosion properties of Mg–3Ca alloys are investigated. The microstructure and X-ray diffraction topography indicate that as-cast Mg–3Ca alloys are composed of primary Mg and eutectic (α-Mg + Mg2Ca) phases, while Mg–3Ca–2Zn alloys are constituted of primary Mg and eutectic (α-Mg + Mg2Ca + Ca2Mg6Zn3) phases. Mechanical properties results show that the element Zn could improve both tensile strength and elongation of Mg–3Ca alloys. The ultimate tensile strength is enhanced by 22%. Meanwhile, the corrosion resistance is increased by the addition of Zn element. It is thought that the presence of Ca2Mg6Zn3 phase mainly contributes to these improvements. Mg–3Ca–2Zn alloy provides moderate strength and excellent corrosion resistance for biomedical application. 相似文献
995.
M. Shanthi M. GuptaA.E.W. Jarfors M.J. Tan 《Materials Science and Engineering: A》2011,528(18):6045-6050
Mg67Zn28Ca5 bulk metallic glass reinforced with 0.66-1.5 vol% of nano alumina particulates were successfully synthesized using disintegrated melt deposition technique. Microstructural characterization revealed reasonably uniform distribution of alumina particulates in a metallic glass matrix. The reinforced particles have no significant effect on the glass forming ability of the monolithic glass matrix. Mechanical characterization under compressive loading showed improved micro hardness, fracture strength and failure strain with increase in nano alumina particulate reinforcement. The best combination of strength, hardness and ductility was observed in Mg/1.5 vol% alumina composite with fracture strength of 780 MPa and 2.6% failure strain. 相似文献
996.
K. Zay E. MaawadH.-G. Brokmeier L. WagnerCh. Genzel 《Materials Science and Engineering: A》2011,528(6):2554-2558
TIMETAL 54M (in the following Ti-54M) is a newly developed (α + β) titanium alloy with nominal composition Ti-5Al-4V-0.6Mo-0.4Fe. The alloy can provide a cost benefit over Ti-6Al-4V due to improved machinability and formability. These attractive properties might be a driving force for replacing Ti-6Al-4V in many aircraft as well as biomedical applications. Since HCF performance is one of the most important requirements for these applications, it is essential to improve this property by microstructural optimization and by mechanical surface treatments such as shot peening or ball burnishing. The latter improvement is mainly the result of induced near-surface severe plastic deformation which results in work-hardening and the generation of compressive residual stresses that retard fatigue crack propagation. The main aim of the present study was to investigate the potential fatigue life improvements in Ti-54M due to shot peening and ball-burnishing. The process-induced residual stresses and stress-depth profiles were determined by energy-dispersive X-ray diffraction (ED) of synchrotron radiation with the beam energy of 10-80 keV. Results on Ti-54M and Ti-6Al-4V will be compared and correlated with the mean stress and environmental sensitivities of the fatigue strengths in the microstructures. 相似文献
997.
HAYNES 282 and HAYNES 230 nickel-based superalloys were subjected to cold rolling deformation and heat treatments in order to investigate processing-microstructure-property relationships to understand the effects of thermomechanical processing on their microstructure and tensile-creep behavior. The sheet materials underwent four cycles of 20% reduction in thickness followed by a solution treatment. The resultant microstructures were characterized using electron backscattered diffraction and electron microscopy, and the high-temperature (973-1088 K (700-815 °C)) creep and fatigue behavior was evaluated and compared to the commercially available sheet alloys. The thermomechanical processing treatments did not significantly affect the grain boundary character distribution and almost half of all the boundaries in the microstructures were twin boundaries. The creep resistance was shown to degrade with the additional thermomechanical treatments, which resulted in finer equiaxed grain sizes. The HAYNES 282 alloy was shown to be significantly more creep resistant than the HAYNES 230 alloy. The fatigue behavior indicated that creep ratcheting occurred more prominently in the HAYNES 230 alloy than in the HAYNES 282 alloy and this was explained to be a result of the superior creep resistance exhibited by the HAYNES 282 alloy. Overall, this study suggests that additional energy-intensive processing treatments, beyond those involved in the commercially available sheet products, may not be beneficial for additional creep resistance. 相似文献
998.
Taehyung KimHyungyil Lee Hong Chul HyunSunghwan Jung 《Materials Science and Engineering: A》2011,528(18):5945-5954
We propose a practical finite element (FE) model for evaluation of peening residual stress. The model aims to produce a solution approaching the endeavored 3D FE solution. We investigate the effect of physical factors including material damping, dynamic friction and strain rate. The kinematical factors including shot diameter and impact velocity are also considered. Integrating those factors and plastic shots, we set up an effective FE model. Based on the arc height and coverage matching with the Almen saturation curve, impact velocity needed for FE analysis is determined. The model is found to provide the solution comparable with the 3D multi-impact FE solution and the experimental XRD result. 相似文献
999.
1000.