材料期刊网

Microstructure and Mechanical Properties of a Duplex Martensite Austenitic Steel Precipitation-hardened by VC Carbide

Changsheng XIE , Jiansheng ZHAO , Peizhen SUN , and Xia LIANG (Dept.of Mech. Eng. Ⅱ , Huazhong University of Science and Technology , Wuhan , 430074 , China)(To whom correspondence should be addressed)

材料科学技术（英文）

This paper presents an investigation on the primary microstructure and mechanical properties of a martensite-austenitic duplex steel precipitation-hardened by VC carbide. The results show that the mechanical properties at room temperature are strongly dependent upon the volume fraction of austenite fA. When fA < 32 % both ultimate strength and Vield strength are decreased with increasing fA. however. whenfA>32%, with increasing the.fA. ultimate strength rises and yield strength drops down. Experimental results at elevated temperatures. show that when test temperature ≤500℃. the yield strength to modulus ratio remains unchanged, however. as the temperature rises a substantial fall in the ratio occurs. The strength values at 600 and 700℃ are increased with increasing strain rate measured by cross-head speed of testing rnachine, The law of mixtures and the contribution of strain-induced transformation from unstable austen ite to martensite to the mechanical properties are discussed.

关键词:

用DEPT135测定Resol的组成及微细结构参数

杨金瑞 , 余尚先 , 顾江楠

高分子材料科学与工程

通过对resol(羟甲基酚化合物和低分子量羟甲基酚树脂)DEPT135图谱的分析讨论,得到一系列计算resol微细结构参数的经验公式.根据DEPT135图谱可判断是否发生缩聚反应,根据经验公式可计算酚单体各个活性点参与反应百分率或酚羟基导入率、不同类型缩聚所占百分率及低分子量羟甲基酚树脂的平均核体数.

关键词: 羟甲基酚化合物 , 羟甲基酚树脂 , DEPT135 , 结构参数

High tensile strength reliability in a bulk metallic glass

Applied Physics Letters

We report high strength reliability under tension of a bulk metallic glass (BMG), demonstrated by its high uniformity in strength found over a statistically significant number of specimens, despite the fact that the samples all showed no macroscopic plasticity. Weibull statistical analysis showed that the Weibull modulus of the material is 36.5, which is much higher than the values of more typical brittle materials, further confirming BMGs' high reliability [Appl. Mech. Rev. 5, 449 (1952)]. (c) 2008 American Institute of Physics.

关键词: plasticity;alloys;temperature;brittleness;estimators;fracture;stress

Fatigue crack initiation and fracture behavior of a copper bicrystal with a perpendicular grain boundary

Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing

By cyclically deforming a [(5) over bar 913]perpendicular to[(5) over bar 79] copper bicrystal with a perpendicular grain boundary (GB), the fatigue crack initiation and fracture behavior were investigated. It was found that only the primary slip systems were activated on both G1[(5) over bar 913] and G2[(5) over bar 79] grains including the vicinity of the GB at axial plastic strain range of 1.8 x 10(-4)-2.56 x 10(-3). By observing the surface and fractography, it was confirmed that the fatigue cracks always nucleated and propagated along the GB, and displayed an obvious tendency on different surfaces. On the front surface of the bicrystal, the intergranular cracking was more preferential than that on the lateral surface, even though the geometrical conditions among PSB, GB and stress axis on the lateral surface claimed to enhance cracking are more close to those proposed by Christ (Mater. Sci. Eng. A117 (1989) L25). Based on the experimental results above, the effect of the interaction of PSB with GB and stress axis on intergranular fatigue cracking in the bicrystal is discussed. It is suggested that Christ's geometrical conditions for intergranular cracking might be further developed and the plastic strain incompatibility near the GB should play a more important effect on intergranular fatigue cracking. (C) 1999 Elsevier Science S.A. All rights reserved.

关键词: copper bicrystal;cyclic deformation;grain boundary;fractography;intergranular cracking;nucleation

Nanoindentation study on elastic and plastic anisotropies of Cu single crystals

Philosophical Magazine

The elastic and plastic anisotropies of three oriented Cu single crystals were determined by a nanoindentation technique with a Berkovich and a cube-corner indenter, respectively. The indentation modulus ( E) of the crystals in the elastic and the plastic regimes were separately extracted using Hertzian elastic analysis and the Oliver-Pharr (O&P) method [J. Mater. Res. 7 1564 ( 1992)]. E values for Cu( 111) and ( 110) are nearly identical, about 20% larger than that of ( 001), as determined using a Berkovich tip in both regimes. E values determined in the plastic regime using a Berkovich tip agree well with theoretical predictions in terms of the Vlassak and Nix [ Phil. Mag. A 67 1065 ( 1993); J. Mech. Phys. Solids 42 1223 ( 1994)] analytical method, but smaller than those determined in the elastic regime. Elastic anisotropies in the plastic regime, however, are not measurable as a cube-corner indenter was used. The hardness ( H) of Cu crystals exhibits an obvious indentation size effect and larger H values are obtained with a sharper indenter.

关键词: indentation experiments;deformation;mechanisms;hardness

形状记忆合金的本构关系

王振清 , 周博 , 梁文彦

金属学报

利用DSC（示差扫描热量分析）热流-温度曲线和马氏体体积分数与自由能增量间的微分关系，建立了一个新的余弦型形状记忆合金马氏体相变模型。在Tanaka和Liang研究的基础上，推导了一个新的形状记忆合金本构方程。研究表明：Liang建立的马氏体相变模型和本构方程分别为本文建立的马氏体相变模型和本构方程所描述的一种特殊情况；本文建立的马氏体相变模型和本构方程比Liang及其它现存马氏体相变模型和本构方程能更准确地描述形状记忆合金的相变行为和力学行为。

关键词: DSC , Shape Memory Alloy , Martensitic transformation model , Constitutive equation

形状记忆合金的本构关系

王振清 , 周博 , 梁文彦

金属学报 doi:10.3321/j.issn:0412-1961.2007.11.017

利用DSC分析了热流-温度曲线和马氏体体积分数与自由能增量间的微分关系,建立了一个新的余弦型形状记忆合金马氏体相变模型;推导了一个新的形状记忆合金本构方程.研究表明:Liang和Rogers的马氏体相变模型和本构方程分别为本文建立的马氏体相变模型和本构方程所描述的一种特殊情况;本文建立的马氏体相变模型和本构方程比Liang和Rogers及其它现存马氏体相变模型和本构方程能更准确地描述形状记忆合金的相变行为和力学行为.

关键词: 形状记忆合金 , DSC , 马氏体相变模型 , 本构方程

合成气预混层流火焰速度的热流量法测量

梁晓晔 , 翁武斌 , 王智化 , 朱燕群 , 周志军 , 周俊虎 , 岑可法

工程热物理学报

本文基于热流量法搭建了层流火焰速度测量平台,通过测量甲烷的绝热层流火焰速度对平台的可靠性进行了验证.然后运用热流量法对15％H2-15％CO-70％N2和12％H2-19％CO-1 3.2％CO2-5.8％CH4-50％N2两种组分合成气的绝热层流火焰速度进行了精确测量,并通过Chemkin 4.1软件采用GRI-Mech 3.0,USC Mech Ⅱ和Davis H2/CO三种机理对试验工况进行了计算.实验数据与计算结果基本一致,尤其与GRI-Mech 3.0机理的计算结果较好地吻合.本文还对实验误差进行了误差分析,对两种合成气的平均测量误差分别达到1.107 cm/s和0.88 cm/s.

关键词: 热流量法 , 合成气 , 绝热层流火焰速度 , 误差分析 , 当量比

TEM OBSERVATION OF ION-PLATED Al FILM ON Ni SUBSTRATE

WAN Lijun Dalian Maritime University , Dalian , Liaoning , China CHEN Baoqing Dalian Institute of Technology , Dalian , Liaoning , China GUO Kexin(K.H.KUO) Institute of Metal Research , Academia Sinica , Shenyang , China Institute of Metal and Technology , Dalian Maritime University , Dalian , Liaoning , China

金属学报(英文版)

A new phase was found at the interface between Al film and Ni substrate when the time of ion-plating reaches 5 min.It was identified to be body centered tetragonal lattice with the constants a=b=0.588 nm,c=0.480 nm.The variation of microstructure and phases with the ion-plating time were observed.Based on these results,the ion-plating film formation mech- anism has been also discussed.

关键词: magnetron sputtering , null , null , null

NUMERICAL ANALYSIS OF THREE-DIMENSIONAL FLUID FLOW AND HEAT TRANSFER IN TIG WELD POOL WITH FULL PENETRATION

WU Chuansong , CAO Zhenning , WU Lin Harbin Institute of Technology , Harbin , China

金属学报(英文版)

A model is established to analyze three-dimensional fluid flow and heat transfer in TICweld pools with full penetration.It considers the deformation of the molten pool surfaceat the condition of full penetrated workpieees,takes the are pressure as the drivingforce of the pool surface deformation,and determines the surface configuration of weldpool based on the dynamic balance of arc pressure,pool gravity and surface tension atdeformed weld pool surface. The SIMPLER algorithm is used to calculate the fluid flowfield and temperature distribution in TIG weld pools of stainless steel workpieces.TIGwelding experiments are made to verify the validity of the model.It shows the calculatedresults by the model are in good agreement with experimental measurements. professor,Dept of Welding Engineering,Harbin Institute of Technology,Harbin 150006,China

关键词: KEY WORDS TIG weld pool , null , null , null , null