SiC_P/Al-Cu复合材料动态再结晶行为及临界条件

Dynamic Recrystallization Behavior and Critical Conditions of SiC_p/A1-Cu Composite

利用Gleeble-1500D热模拟试验机对40%SiC_P/Al-Cu复合材料进行压缩实验,研究其在温度为350~500℃、应变速率为0.01~10 s^(-1)条件下的高温塑性变形行为。由实验得出变形过程中的应力-应变曲线,采用加工硬化率处理方法对应力-应变数据进行处理,结合lnθ-ε曲线的拐点和(-α(lnθ)/αε)-ε曲线最小值的判据,研究该复合材料动态再结晶临界条件。结果表明:40%SiC_P/Al-Cu复合材料的应力-应变曲线主要以动态再结晶软化机制为特征,峰值应力(σ_p)随变形温度的降低或应变速率的升高而增加;该材料的lnθ-ε曲线出现拐点,(-α(lnθ)/αε)-ε曲线出现最小值;临界应变(ε_c)随变形温度的升高与应变速率的降低而减小,且临界应变与峰值应变(εp)之间具有相关性,即ε_c=0.528εp;临界应变与Zener-Hollomon参数(Z)之间的函数关系为ε_c=4.58×10^(-3)Z^(0.09)。透射电镜观察显示应变为0.06时(变形温度为400℃,应变速率为10 s^(-1))已经发生动态再结晶,应变为0.2时,动态再结晶晶粒充分长大。

Using the Gleeble-1500D simulator, the high temperature plastic deformation behavior of 40% SiCp/Al-Cu composite were investigated at 350-500 with the strain rate of 0. 01-10 s 1. The stress-strain curves were obtained during the tests. The critical con-ditions of dynamic recrystallization for onset of DRX during deformation of 40% SiCP/Al-Cu composite was obtained by computation of the strain hardening rate （ θ ） from initial stress-strain data and introduction of the inflection point criterion of In θ -ε curves and the min-imum value criterion of （ - （ln π ） / ε ） - ε ） curves. The results indicate that the softening mechanism of the dynamic recrystallization is a feature of high-temperature flow stress strain curves of the composites, and the peak stress increases with the decrease of deforma-tion temperature or the increase of strain rate. The inflection point in the In θ-ε curve appears, and the minimum value of the （- （ In θ ）/ ε）-ε） curve is presented when the critical state is attained for this composite. The critical strain decreases with the de-crease of strain rate and the increase of deformation temperature. There is linear relationship between critical strain and peak strain, i. e. εc= 0. 528εp. The predicting model of critical strain is described by the function of εc=4. 58× 10 ^-3Z 0.09. Electron microscopic a-nalysis show that the dynamic recrystallization occurs when the strain is 0. 06 （ T = 400 ℃ , ε = 10 s -1 ） , and the dynamic recrystalli-zation grains fully grow up when the strain is 0. 2.