SiC_w／LD2复合材料超塑变形过程中的织构变化

CHANGE OF TEXTURE IN A SiC_w/LD2 COMPOSITE DURING SUPERPLASTIC DEFORMATION

用挤压铸造法制成ＳｉＣ_ｗ／ＬＤ２复合材料，在４７０℃下进行热挤压得到板材，挤压比为１：２２．在５７０℃进行超塑拉伸实验，拉伸速度由１ｍｍ／ｍｉｎ逐步升至５ｍｍ／ｍｉｎ时获得了最大延伸率２８０％．用Ｘ射线衍射法对超塑拉伸过程中基体和晶须的织构变化进行了研究．结果表明，在超塑拉伸过程中基体的织构要发生漫散，同时有再结晶织构出现，这种再结晶织构也会随拉伸的进行而漫散．晶须在拉伸过程中要发生转动，这种转动主要是θ转动，基本上不发生ω转动．

SiC_2 / LD_2 compoiste has been fabricated by using squeeze casting method and then hot extruded at 743 K and the estruded ratio is 1:22. The superplastic tensile tests were carried out in the temperature range from 773 K to 853 K and in the strain rate range from 8.33×10￣(-4) s￣(-1) to 8.33×10￣(-3)s￣(-1) A maximum elongation of 280% occured at a strain rate of 2×10￣(-3) s￣(-1) at 843 K. The texture of the composite has been studied in two directions by means of anti-pole figure. The results manifest that the texture of metal matrix diffuses during the superplastic deformation and the new recrystallized texture emerges at the beginning of deformation. The recrystallized texture diffuses with the progress of elongation and is similar to the original texture. This is related to the confused rotation of grains. The whiskers will rotate by the means of θrotation