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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制备了SiC颗粒增强7075铝合金，SiC颗粒的体积分数分别为5%、10%和15%（MA 7075 +5SiC、+10 SiC、+15 SiC复合材料）。这些复合材料的超塑性性能进行了研究，在初始应变速率范围从10^<-5>s^<-1>到2 × 10 ^s^，<-1>在793 K。1的温度。预应变后，SiC颗粒在基体中均匀分布，形成了平均晶粒尺寸小于1 μ m的极细晶粒组织.在三种复合材料的对数流变应力-对数应变速率曲线中，两个应变速率区域显示出低和高的应变速率敏感性指数，m，（区域1和2，分别）被确认，在通常观察到的超塑性。在从5 × 10 - 4到2 × 10 - 4 s-4的非常高的应变速率下<-1><-1>（区域2），m值大于0.36，并且三种复合材料的超塑性伸长率大于200%。相比之下，在较低的应变率（区域1）下，m值小于0.13，其中出现低延伸率（< 50%）。3.随着SiC颗粒含量的增加，区域2向高应变速率区移动。晶界滑动在2区比1区更明显，用外推法估算的门槛应力σ<th>_随着SiC含量的增加而增加.对于MA 7075+SiC复合材料，应变速率和有效应力σ_e（=sigma-sigma_e）的双对数曲线<th>可以近似为斜率约为0.5的直线。复合材料的高应变率超塑性可以用位错滑移容纳的晶界滑动模型来解释。晶界上的SiC颗粒能够抵抗晶界滑移，从而产生门槛应力σ_i<th>。