n-SiC_P/AZ61镁基复合材料的半固态压缩变形行为

Compression Deformation Behavior of Semisolid n-SiC_P/AZ61 Magnesium Matrix Composites

采用Gleeble1500D模拟试验机,对半固态n-SiCP/AZ61复合材料进行触变等温压缩试验,分析不同因素(应变速率、变形温度、增强相质量分数)对真实应力—应变曲线的影响,并对其触变压缩变形机制和触变压缩后的显微组织进行探讨和研究。结果表明:当增强相质量分数相同时,随着应变速率的减少,真实应力出现下降;随着应变温度的增加,真实应力—应变曲线的峰值应力值显著减小。随纳米SiC颗粒质量分数的增加,n-SiCP/AZ61复合材料在半固态条件下触变压缩变形过程中的变形抗力也相应增加。复合材料在触变压缩变形过程中,其变形过程可分为'上升'、'下降'和'平稳'三个阶段,第一阶段的主要变形机制为固相颗粒间的滑移机制和固相颗粒的塑性变形;第二阶段的主要变形机制为液—固相颗粒混合流动机制、固相颗粒间的滑移机制和固相颗粒的塑性变形;第三阶段的主要变形机制为固相颗粒间的滑移机制和固相颗粒的塑性变形。

Simulation testing machine Gleeble1500D is employed to carry out tixotropic isothermal compression experiments for semi-solid n-SiCP/AZ61 composites.The effects of different factors（strain rate,deformation temperature and reinforcing phase mass fraction） on true stress-strain curves are analyzed.And semi-solid tixotropic compression deformation mechanism and microstructure after tixotropic compression of n-SiCP/AZ61 composites are discussed.The results show that the true stress decreases with the decrease of strain rate,and the peak stress value of true stress-strain curve reduces markedly with the increase of strain temperature.And the deformation resistance of n-SiCP/AZ61 composites under semi-solid tixotropic compression deformation process increases with the increase of nano-SiC particles.According to stress-strain curves,the deformation process can be divided into three stages,i.e.＂rising＂,＂falling＂ and ＂stable＂.Their main deformation mechanisms are respectively slip between solid particles and plastic deformation of solid particles;mixing flow of liquid-solid particles,slip between solid particles and plastic deformation of solid particles;slip between solid particles and plastic deformation of solid particles.