Development of High Strain Rate Superplastic Aluminum-SiC Particulate Composits

高应变率超塑性铝-SiC颗粒复合材料的开发

基本信息

批准号：
04452279
负责人：
MATSUKI Kenji
金额：
$ 4.1万
依托单位：
TOYAMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04452279/
关键词：
Composit High Strain Rate Superplasticity Mechanical Alloying Aluminium Alloy SiC Particurate Fine Grain Size m value Threshold stress アルミニウム基複合材料炭火珪素粒子破断伸び微細結晶料動的再結晶変形応力粒界すべり

项目摘要

7075 aluminum alloys reinforced with SiC particulates, of which volume fractions are 5,10, and 15 % (MA7075+5SiC,+10SiC,+15SiC composite, respectively), have been developed by using mechanical alloying process. Superplastic properties of these composites have been investigated at the initial strain rates ranging from 10^<-5> s^<-1> to 2x10 s^<-1> at a temperature of 793 K.1. After the pre-straining, SiC particulates are distributed uniformly within matrix, and a extremely fine grain structure, with average grain size less than 1 mu m is developed.2. In log flow stress-log strain rate curves for the three composites, two strain rate regions showing low and high strain rate sensitivity exponent, m, (region 1 and 2, respectively) were recognized, as in usually observed in superplasticity. At very high strain rates from 5x10^<-1> to 2x10 s^<-1> (region 2), values of m were larger than 0.36, and superplastic elongations were larger than 200% in the three composites. In contrast, m values were less than 0.13 at lower strain rates (region 1), where low elongations (< 50%)appeared.3. With increasing of the SiC particulate content, region 2 moved to the range of higher strain rate. Grain boundary sliding took place more remarkably in region 2 rather than in region 1.The threshold stress, sigma_<th>, estimated by using an extrapolation method increased with increasing of the SiC content.4. A double logarithmic plot of the strain rate and the effective stress, sigma_e (=sigma-sigma_<th>), can be approxi- mated by straight lines with a slope of about 0.5 for MA 7075+SiC composites.5. The high strain rate superplasticity of the composites can be explained by the grain boundary sliding model accommodated by dislocation slip. The SiC particulates on grain boundaries can resist the boundary sliding, thus resulting the threshold stress, sigma_<th>.

采用机械合金化工艺开发了体积分数为5%、10%和15%的SiC颗粒增强7075铝合金（分别为MA7075+5SiC、+10SiC、+15SiC复合材料）。在 793 K.1 的温度下，在 10^-5s^-1> 至 2x10s^-1> 的初始应变率下研究了这些复合材料的超塑性。预应变后，SiC颗粒均匀分布在基体中，形成极细的晶粒结构，平均晶粒尺寸小于1μm。 2．在三种复合材料的对数流动应力-对数应变率曲线中，识别出显示低应变率敏感性指数 m 和高应变率敏感性指数 m 的两个应变率区域（分别为区域 1 和区域 2），正如通常在超塑性中观察到的那样。在从 5x10^<-1> 到 2x10s^<-1>（区域 2）的极高应变率下，三种复合材料的 m 值大于 0.36，超塑性伸长率大于 200%。相反，在较低应变率（区域1）下，m 值小于0.13，出现低伸长率（< 50%）。3．随着SiC颗粒含量的增加，区域2移动到较高应变率的范围。晶界滑动在区域2中比在区域1中发生更显着。使用外推法估计的阈值应力sigma_<th>随着SiC含量的增加而增加。4．对于 MA 7075+SiC 复合材料，应变率和有效应力 sigma_e (=sigma-sigma_<th>) 的双对数图可以通过斜率约为 0.5 的直线来近似。5。复合材料的高应变率超塑性可以通过位错滑移所适应的晶界滑动模型来解释。晶界上的SiC颗粒可以抵抗晶界滑动，从而产生阈值应力sigma_<th>。