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Monte Carlo Simulation of B2-L2_1 Ordering Transitions in Au-Cu-Al Alloy Systems

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Journal of Shanghai Jiaotong university(science) 2011年第2期16卷 186-189页

作者：丁洪徐斌倪昶王京阳金学军 Department of materials science and Engineering Shanghai Jiaotong University shenyang national laboratory for materials science Institute of Metal ResearchChinese Academy of Sciences

The B2-L21 ordering transitions in Au-Cu-Al shape-memory alloys are studied by the Monte Carlo exchange simulations,where a set of the first,the second and the third nearest-neighbor mixing potentials for CuAl in the Au-Cu-Al alloys are calculated from first principals using the Connolly-Williams *** ensure the phase stability of the β-Au-Cu-Al,the investigation includes the range of compositions Au2Cu1-xAl1+x (0.15≤x≤0.15).The B2-L21 transition temperatures are predicted,and are in agreement with the experimental *** atomic ordering around vacancy of the L21 structure is further discussed.

关键词： Au-Cu-Al alloys B2-L21 transitons Monte Carlo simulation vacancy

An Examination on Atomic-level Stress Calculations by Nanoindentation Simulation via the Quasicontinuum Method

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Journal of materials science & Technology 2010年第1期26卷 56-64页

作者： Yufei Shao and Shaoqing Wang shenyang national laboratory for materials science, institute of metal research, chinese academy of sciences, shenyang 110016, china [a] shenyang national laboratory for materials science institute of metal research chinese academy of sciences shenyang 110016 china

Nanoindentation simulations on single crystals AI and Cu via the quasicontinuum method have been performed. Two kinds of atomic-level local stress calculation methods, i.e. the coarse-grained local stress and the virial local stress, are employed to calculate the stress state of the contact area. Various comparisons between the coarse-grained local stress and the virial local stress have been made. Firstly, the averaged normal stress beneath the contact surface calculated by coarse-grained method agrees well with continuum mechanical pressure measurement, while the virial method gives unphysical results sometimes. Secondly, the coarsegrained results reflect the indenter size effect on the critical shear stress quite accurately, while the virial calculations fail. Thirdly, the distribution of maximum shear stress of the coarse-grained method predicts the defects nucleation locations reliably, while the distribution of virial local stress gives an incorrect prediction sometimes. Thus it is concluded that the coarse-grained method can offer a more reliable description of the local stress states of atoms in spatially inhomogeneous solids.

关键词： Nanoindentation Atomistic stress Quasicontinuum

Vibration Effects on the Structural Stability of Al-Ti Intermetallics by First-principles Calculations

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Journal of materials science & Technology 2010年第12期26卷 1071-1077页

作者： Hui Zhang and Shaoqing Wang shenyang national laboratory for materials science,institute of metal research,chinese academy of sciences,shenyang 110016,china [a] shenyang national laboratory for materials science institute of metal research chinese academy of sciences shenyang 110016 china

The structural stability of the intermetallics AlTi3, Al2Ti, Al3Ti4 and Al3Ti in the Al-Ti system has been investigated using density functional theory （DFT） and density functional perturbation theory （DFPT）. The calculated ground-state convex hull is in agreement with the experimental researches. Al3Ti4 （hP7） is metastable at 0 K and may be stabilized as the temperature increases due to the effects of the vibration entropy. For Al2Ti, r-Al2Ti is stable at 0 K and h-Al2Ti is stabilized by the vibration entropy at high temperatures. Al3Ti （tI16） is unstable considering vibration effects and Al3Ti （tI8） is the most stable structure at 0 K.

关键词： First-principles Al-Ti Vibration Crystal structure

A Novel Deflection Method for Measuring the Growth Stress of Thermally Growing Oxide Scales

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Journal of materials science & Technology 2003年第3期19卷 231-234页

作者： Yuhai QIAN Meishuanshenyang national laboratory for materials science, institute of metal research, chinese academy of sciences, shenyang 110016, china Lab. for Mat. Sci. Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China

A kind of new deflection technique has been developed for measuring the growth stress of thermally growing oxide scales during high temperature oxidation of alloys. The average growth stresses in oxide scales such as Al2O3, NiO and Cr2O3 formed on the surface of the superalloys can be investigated by this technique. Unlike the comventional deflection method, the novel method does not need to apply a coating for preventing one main face of thin strip specimen from oxidizing and can be used under the condition of longer time and higher temperature.

关键词： Oxide film Growth stress Deflection method

Strain-induced Microstructure Refinement in a Tool Steel Subjected to Surface Mechanical Attrition Treatment

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Journal of materials science & Technology 2010年第3期26卷 258-263页

作者： Shoudan Lu,Zhenbo Wang and Ke Lu shenyang national laboratory for materials science,institute of metal research,chinese academy of sciences,shenyang 110016,china [a] shenyang national laboratory for materials science institute of metal research chinese academy of sciences shenyang 110016 china

A nanostructured surface layer has been fabricated on an AISI H13 tool steel by means of surface mechanical attrition treatment （SMAT）.Strain-induced refinement processes of ferrite grains and carbide particles have been investigated by transmission electron microscopy （TEM） and scanning electron microscopy （SEM） in the SMAT surface *** refinement of ferrite is found to be dominated by dislocation activities and greatly facilitated by a large number of carbide particles at a depth 〉20 μ*** comparisons with microstructure refinement processes in other SMAT ferrite steels indicate that a larger volume fraction of carbide particles with a lower shear strength is expected to facilitate the refinement process of ferrite grains.

关键词： Nanostructured and nanocrystalline material AISI H13 tool steel Grain refinement Surface mechanical attrition treatment (SMAT) Carbides

Microstructure Investigation on the Triple Junction with an Adjoining Twin Boundary in Nanocrystalline Palladium

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Journal of materials science & Technology 2010年第11期26卷 1047-1050页

作者： Yuchen Wang,Zhenxing Su and Dehai Ping shenyang national laboratory for materials science,institute of metal research,chinese academy of sciences,shenyang 110016,china [a] shenyang national laboratory for materials science institute of metal research chinese academy of sciences shenyang 110016 china

By using high-resolution transmission electron microscopy,a [110] triple junction （TJ） containing a twin boundary （TB） in nanocrystalline palladium has been observed along the common axis *** statics calculation and imaging simulation were performed to determine the atomic structure of the *** modeling structure exhibits that the adjoining TB is a distorted one,whilst other two adjoining grain boundaries （GBs） exist in steady equilibrium *** present observation gives a clear example demonstrating that the adjoining TB can release the larger stresses residing at the junction.

关键词： Triple junction Grain boundary Molecular statics High-resolution transmission electron microscopy (HRTEM)

Growth and Microstructure of r.f. Sputtered Fe/Ti Multilayers

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Journal of materials science & Technology 2001年第5期17卷 521-524页

作者： Wei WANG shenyang national laboratory for materials science, institute of metal research, chinese academy of sciences, shenyang 110016, china Lishi WEN Department of Surface Engineering of materials, institute of metal research, chinese academy of science chinese Acad Sci Inst Mat Res Shenyang Natl Lab Mat Sci Shenyang 110016 Peoples R China chinese Acad Sci Inst Mat Res Dept Surface Engn Mat Shenyang 110016 Peoples R China

Fe/Ti multilayers with different modulation wavelengths (Lambda) prepared by r.f. sputtering has been investigated by using cross sectional transmission electron microscopy (XTEM). It was observed that the columnar structure, interface morphology, and metastable phase presented at the interface of the multilayer system strongly depend on the bilayer thickness (Lambda). For high period multilayers, the waviness wavelength of interfaces is about two times broader than the column diameter. For a sample with Lambda =30 nm, its column width and waviness wavelength was about 80, and 190 nm, respectively. Both of them decreased with the reduction of Lambda, so as to nearly equal values of column diameter and waviness wavelength were obtained. The Fe and Ti grains of both 30 nm and 6 nm multilayers are polycrystalline, and have a textured structure. In short bilayer thickness (Lambda =6 nm), the intermetallic compound Fe2Ti was presented at the interfaces due to solid state reaction; for Lambda =2 nm, amorphous phase Ti-rich layer was formed at the interfaces, resulting in a sharp interface multilayer structure.

关键词： Ti Growth and Microstructure of r.f Sputtered Fe/Ti Multilayers Fe

Mechanical Properties and Temper Resistance of Deformation Induced Ferrite in a Low Carbon Steel

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Journal of materials science & Technology 2010年第12期26卷 1107-1113页

作者： Luhan Hao,Namin Xiao,Chengwu Zheng and Dianzhong Li shenyang national laboratory for materials science,institute of metal research,chinese academy of sciences,shenyang 110016,china [a] shenyang national laboratory for materials science institute of metal research chinese academy of sciences shenyang 110016 china

The microstructures and mechanical properties of deformation induced ferrite （DIF） in the low carbon steel Q235 under different deformation temperatures have been investigated systematically. Through deformation induced ferrite transformation （DIFT）, ferrite grain can be refined to 3 μm and accounts for above 85% of the overall fraction. Yield strength of DIF （〉500 MPa） is increased by up to 100% compared with the conventional low carbon steel. Comparison of microstructure and mechanical properties in the Q235 steel with DIF and tempered DIF microstructure illustrates that the strengthening mechanism of DIF microstructure is the combination of grain boundary strengthening and carbon supersaturated strengthening. Electron back-scattered diffraction （EBSD） analysis and high magnification scanning electron microscopy （SEM） observation denote that high-angle grain boundary among ultrafine ferrite grain and the transformation product of retain austenite membrane along ferrite boundaries are responsible for the stability of ferrite grain size during tempering process. Transmission electron microscopy （TEM） analysis demonstrates that the transformation product of retained austenite membrane between ferrite grain boundaries is cementite.

关键词： Low carbon steel Deformation Mechanical properties Temper induced ferrite transformation Grain size resistance

Transformation Behavior of Precipitates in a W-alloyed 10 wt pct Cr Steel for Ultra-supercritical Power Plants

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Journal of materials science & Technology 2010年第9期26卷 817-822页

作者： Xiaoqiang Hu,Namin Xiao,Xinghong Luo and Dianzhong Li shenyang national laboratory for materials science,institute of metal research,chinese academy of sciences,shenyang 110016,china [a]shenyang national laboratory for materials science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

Thermodynamic calculation,thermal analysis,and identification and observation of precipitates have been carried out on a W-alloyed 10 wt pct Cr steel by means of ThermoCalc program,differential thermal analysis（DTA）,X-ray diffraction（XRD） and transmission electron microscopy（TEM） with an energy dispersive Xray spectrometer,*** critical phase transformation points were determined by combining experimental results with *** individually stable phases of Nb（C,N） and VN,instead of one single phase MX（X：C,N）,M23C6 or Laves phases,were predicted in the calculated equilibrium phase *** unstable elongated M7C3 with relatively higher Cr was detected unexpectedly in the normalized and tempered *** kinds of spherical Nb（C,N） with different size were recognized as the primary and the secondary precipitates of Nb（C,N） which contain different V *** was observed that one kind of complex precipitate in a special V-wing shape was resulted from two plate-like VN adhering to coarse primary spherical Nb（C,N）.

关键词： Heat resistant steel Phase transformation Microstructure MX(X:C N) precipitate