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Effects of grain-boundary liquid particles on fracture of a copper bicrystal

晶界液体颗粒对铜双晶断裂的影响

基本信息

批准号：
10650687
负责人：
ONAKA Susumu
金额：
$ 2.18万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

The main purposes of this project are to understand(1) the roles of liquid particles on grain boundaries in high- temperature fracture, and(2) the effects of dispersed particles on various mechanical properties of composites. Experimental work to study, deformation and fracture behavior of Cu-BィイD22ィエD2OィイD23ィエD2 and Cu-GeOィイD22ィエD2 alloys and theoretical work using micromechanics are made.Cu alloys containing small BィイD22ィエD2OィイD23ィエD2 or GeOィイD22ィエD2 glass particles have been made by internal oxidation treatments. Both the particles are dispersed in-grain and on-grain-boundaries of Cu matrix. Although the GeOィイD22ィエD2 particles in Cu are considered as plastically non-deformable solid, the BィイD22ィエD2OィイD23ィエD2 particles become liquid particles at high temperatures. From results of tensile tests using the Cu-BィイD22ィエD2OィイD23ィエD2 and Cu-GeOィイD22ィエD2 alloys at various temperatures, the roles of liquid particles on grain boundaries in high-temperature grain-boundary fracture have been discussed. The liquid BィイD22ィエD2OィイD23ィエD2 particles on grain boundaries cause brittle fracture of the Cu alloy. Void formationin the liquid particles is the reason of this fracture.Stress relaxation caused by the combination of interfacial sliding and diffusion around spherical inclusions has been discussed. Rate equations of the relaxation processes have been derived. Effects of shape and volume fraction of second phase on stress states in two-phase materials have been evaluated. The average field method has been applied for the prediction of stable shapes of coherent precipitates under uniaxial stresses. Effects of Poisson's ratio on the variation of the average Young's moduli of composites with the transitions of second-phase shape have been discussed.

本计画的主要目的是了解（1）高温断裂时，液态粒子对晶界的作用，以及（2）分散粒子对复合材料各种机械性质的影响。本文对Cu-B系D22微晶D2O微晶D23微晶D22和Cu-GeO微晶D22微晶D23微晶D22合金的变形和断裂行为进行了实验研究和细观力学理论分析。这两种颗粒都分散在Cu基体的晶内和晶界上。虽然Cu中的GeO双金属D22双金属D2颗粒被认为是塑性不可变形的固体，但B双金属D22双金属D2O双金属D23双金属D2颗粒在高温下变成液体颗粒。本文根据Cu-B系合金D22晶界D2O系合金D23晶界D2和Cu-GeO系合金D22晶界D2在不同温度下的拉伸试验结果，讨论了晶界上的液态颗粒在高温晶界断裂中的作用。晶界上的液态B相D22相D2O相D23相D23相是导致Cu合金脆性断裂的主要原因。本文讨论了界面滑移和球形夹杂物周围扩散共同作用引起的应力松弛。导出了弛豫过程的速率方程。研究了第二相形状和体积分数对两相材料应力状态的影响。平均场方法已被应用于预测稳定的形状共格沉淀物在单轴应力。讨论了泊松比对复合材料平均杨氏模量随第二相形状转变的影响。