低温预变形对SiC_p/MR64复合材料超塑性的影响

EFFECT OF PRIOR WARM-DEFORMATION ON SUPERPLASTICITY IN SiC_p / MR64 COMPOSITES

用拉伸实验研究了低温预变形对碳化硅颗粒增强MR64复合材料超塑性的影响。材料在500℃,应变速率为8.33×10^(-3)s^(-1)的条件下拉伸,超塑变形延伸率达到210％,材料经过300℃低温预拉伸至35％的变形量以后,在超塑条件下拉伸延伸率达305％。通过对显微组织、孔洞的观察发现,低温预变形产生的形变组织在超塑变形初期发生了动态再结晶,晶粒尺寸得到进一步细化,孔洞面积率明显减少。低温预应变提高超塑性的主要原因在于它减少了变形过程中孔洞的数量。

The effect of prior warm-deformation on superplasticity was studied by means of tensile tests for SiCp / MR64 composites. 10%SiCp / MR64 showed tensile elongations in excess of 210% at an initial strain rate of 8.33 10-3s-1at 500℃ , and after prior-worked to 35% at 300℃ the maximum elongation of 305% was obtained for superplastic test. Metallographic and cavitation behavior observations showed that continuous recrystallization took place in materials prior-worked during superplastic deformation, which fined the grain sizes, and the prior-working process also reduced the level of cavitation. It is concluded that the decreased number of cavites is the main reason for the improved superplastic ductility.