MB2/SiC复合材料的高应变速率超塑性

High strain rate superplasticity in MB2/SiC magnesium matrix composites

用搅拌法制备了以MB2为基、以SiC颗粒为增强体的镁基复合材料 ,铸锭在 390℃热挤压成棒材。在温度为 380～ 560℃和应变速率为 2 .0 8× 1 0 - 3s- 1 ～ 5 .2 1× 1 0 - 1 s- 1 的范围内 ,测试了挤压态MB2 / 1 0 %SiC(体积分数 )和MB2 / 5 %SiC镁基复合材料的超塑性。MB2 / 1 0 %SiC在温度为 52 5℃、应变速率为 2 .0 8× 1 0 - 1 s- 1 时最大延伸率可达 2 2 8% ,应变速率敏感性指数为 0 .39。

Ingots of MB2 (magnesium based alloy) matrix composites reinforced with SiC particulates (2 μm), of 10% or 5%(in volume fraction) were prepared by stir casting and then extruded with a reduction ratio of 49∶1 at 390 ℃. Superplasticity of the composites was investigated at 380 ℃～560 ℃ and with strain rate from 2.08×10 -3 ?s -1 to 5.21×10 -1 ?s -1 . The maximum of total elongation as high as 228% was obtained in MB2/10%SiC composite at 525 ℃ with a strain rate of 2.08×10 -1 ?s -1 , and the strain rate sensitivity exponent (m) was 0.39. Filament was observed on the fracture surface of the specimens showing superplasticity.