SiC<sub>P</sub>/ Ni 纳米复合材料的超塑性

SiC_P/ Ni 纳米复合材料的超塑性

摘要: 研究了SiC_P / Ni 纳米复合材料的超塑性。SiC_P / Ni 采用脉冲电沉积方法获得。拉伸实验温度为410 ℃和450 ℃, 应变速率范围为8.3 ×10 ^-4～ 5 ×10 ^-2 s ^-1 。温度为450 ℃、应变速率为1.67 ×10 ^-2 s^-1时, 获得的最大延伸率为836 %。采用SEM、TEM 分析了沉积态材料的表面形貌、断口形貌及变形后的组织, 并对变形机理进行了探讨。通过SiC 颗粒稳定基体组织有利于实现材料的超塑性, 低空洞体积分数有助于获得大延伸率。晶粒长大到微米尺度时, 变形机制主要是位错协调的晶界滑移和位错滑移塑性。

Abstract: Superplasticity of the pulse elect rodeposited SiC_P / Ni nanocomposite was investigated by tensile test s.St rain rates range f rom 8.3 ×10 ^-4 to 5 ×10 ^-2 s ^-1 , and the selected temperatures are 410 ℃and 450 ℃. A maximumelongation of 836 % was obtained at the st rain rate of 1.67 ×10 ^-2 s ^-1 and temperature of 450 ℃. Surface morphology , f racture surfaces and deformed microst ructure were observed by SEM and TEM. The deformation mechanismwas analyzed. SiC has a favorable effect on the superplasticity of the material by enhancing the microst ructural stability. A low volume f raction of cavity was helpful to obtain high elongation. The main deformation mechanisms aredislocation accommodated grain boundary sliding and dislocation slip plasticity when the grains grow to micro size.