Fatigue Tests of Copper Single Crystals with Martensitically Transformable Small Dispersed Iron Particles

马氏体相变小弥散铁颗粒铜单晶的疲劳试验

基本信息

批准号：
03650571
负责人：
KATO Masaharu
金额：
$ 1.22万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

It is known that proper heat treatment can produce coherent gamma-iron or incoherent alpha-iron fine precipitate particles in a copper matrix. It is also known that plastic deformation induces gamma*alpha martensitic transformation in the coherent gamma-iron particles. The purpose of this research is to examine the effects of these particles on the fatigue behavior and on the development of fatigue dislocation structure using Cu-Fe alloy single crystals.When Cu-Fe alloy specimens were cyclically deformed under plastic strain control. cyclic hardening was observed regardless of the type (coherent or incoherent) of the particles. The lack of cyclic softening is attributed to the fact that initially coherent gamma-iron particles transform martensitically into incoherent alpha-iron in the early stage of the cyclic deformation. In any specimen, the so-called plateau region was found to exist in the cyclic stressstrain curves. However, different from copper single crystals where the characteristic ladder dislocation structure is observed in the plateau region, dislocations were more irregular and tangled in the Cu-Fe alloy single crystals. This is indicative of the strong effect of dispersed particles on preventing the dislocation rearrangement to form characteristic fatigue dislocation structure.It is concluded from this study that unlike usual coherent dispersed particles, the coherent gamma-iron particles are very effective in improving fatigue resistance of copper because of their transformability.

众所周知，适当的热处理可以在铜基体中产生相干的γ-铁或不相干的α-铁细沉淀颗粒。还已知塑性变形会在连贯的伽马铁颗粒中引起伽马*α马氏体转变。本研究的目的是利用 Cu-Fe 合金单晶检验这些颗粒对疲劳行为和疲劳位错结构发展的影响。当 Cu-Fe 合金试样在塑性应变控制下循环变形时。无论颗粒的类型（相干或非相干），都观察到循环硬化。循环软化的缺乏归因于这样的事实：在循环变形的早期阶段，最初相干的γ铁颗粒以马氏体方式转变为非相干的α铁。在任何样本中，都发现循环应力应变曲线中存在所谓的平台区域。然而，与铜单晶在高原区域观察到特征性阶梯位错结构不同，Cu-Fe合金单晶中的位错更加不规则和缠结。这表明弥散颗粒对防止位错重排形成特征性疲劳位错结构具有很强的作用。从这项研究得出的结论是，与通常的共格弥散颗粒不同，共格γ铁颗粒对于提高铜的抗疲劳性能非常有效。因为它们的可变形性。