挤压铸造铝基复合材料的高应变速率超塑性

HIGH STRAIN RATE SUPERPLASTICITY OF ALUMINUM MATRIX COMPOSITE MADE BY SQUEEZE CASTING

用挤压铸造、挤压比仅为１０∶１的挤压以及进一步的轧制成功地制备了具有高应变速率超塑性行为的βＳｉＣ晶须增强ＬＹ１２复合材料。该复合材料晶粒细小，约为２μｍ；在温度为８０３Ｋ和初始应变速率为１．１×１０－１ｓ－１时，延伸率达３５０％，应变速率敏感系数ｍ值约为０．３５；超塑性变形的主要机制是细小晶粒的晶界滑动，适当的微量液相有利于该复合材料的高应变速率超塑性。

A SiC whisker reinforced LY12 aluminum composite expected to exhibit high strain rate superplasticity has been successfully fabricated by squeeze casting and rolling after extrusion with a low extrusion ratio of 101. The asprocessed composite has a fine grain size of about 2 m, and exhibits a maximum total elongation of 350% and a strain rate sensitivity of about 0.35 at the initial strain rate of 1.110-1s-1 at 803 K. The dominant process of superplastic deformation is fine grain boundary sliding, and an appropriately small amount of liquid phase can enhance the high strain rate superplasticity of the composite.