10 vol%TiC/Cu-Al_2O_3复合材料热变形及动态再结晶行为

Hot deformation and dynamic recrystallization behavior of 10 vol% TiC /Cu-Al_2O_3 composite

利用Gleeble-1500D热力模拟试验机，在温度为450～850℃、应变速率为0．001～1s^-1、真应变量0．7的条件下，研究和分析10vol％TiC／Cu—Al2O3复合材料高温塑性变形及动态再结晶行为。结果表明，材料的高温流变应力-应变曲线主要以动态再结晶软化机制为特征，峰值应力随变形温度降低或应变速率升高而增加，属于温度和应变速率敏感材料；材料热激活能为170．737kJ／mol；其硬化率-应力（θ-σ）曲线均呈现拐点且-dθ／dσ-σ曲线出现极小值；临界应变随应变速率的增大及变形温度的降低而增加，且临界应变（εc）与峰值应变（εp）之间具有一定相关性，即εc／εp=0．704；临界应变与Z参数之间的函数关系为εc=1．48×10^-2Z^0.0765.

Using Gleeble-1500D simulator, the high-temperature plastic deformation behavior and dynamic recrystallization behavior of 10 vol% TiC/Cu-Al2O3 composite were investigated at 450 -850 ℃ with strain rate of 0. 001 -1 s^-1 and total strain of 0. 7. The results show that the softening mechanism of the dynamic recrystallization is a feature of high-temperature flow stress-strain curves of the composite, and the peak stress increases with the decreasing of deformation temperature or the increasing of strain rate, and the composite belongs to temperature and strain rate sensitive material. Based on the true stress-strain curves, the activation energy of the composites is 170. 737 kJ/mol. Meanwhile, the inflection point in the θ - σ curve appears and has a minimum value in the - dθ/dσ - σ curve when the critical state is attained for this composite. The critical strain increases with the increasing strain rate and the decreasing deformation temperature. There is linear relationship between critical strain and peak strain, i. e. , εc/εp = 0. 704. The predicting model of critical strain is described by the equation： εc = 1.48×10^-2Z^0.0765.