电沉积纳米镍合金及其复合材料的超塑性

Superplasticity of nanostructured nickel alloy and composite fabricated by electrodeposition

采用脉冲电沉积技术制备纳米镍合金及Ni/Si3N4（w）复合材料,在应变速率为1×10-3^-2×10^-2 s^-1,温度为673-823 K的条件下,研究它们的超塑性拉伸变形行为,确定最佳超塑性条件并获得最大伸长率。结果表明,Ni-Co合金在773 K,应变速率5×10^-3 s^-1时,最大伸长率为279%;Ni/Si3N4（w）复合材料在713 K,应变速率1×10^-2 s^-1时,最大伸长率为635%。采用SEM和TEM对电沉积和超塑变形前后试件的显微结构进行表征。应用晶粒长大行为和协调机制对合金和复合材料的超塑性进行对比研究和讨论。

A nanostructured nickel alloy and a Ni/Si3N4（w） composite were fabricated by pulse current electrodeposition, and their superplastic tensile deformation behaviors were investigated at strain rates ranging from 1× 10^-3 to 2×10^-2 s^-1 and temperatures ranging from 673 to 823 K. Optimal superplastic condition and the maximum elongation were determined. The results show that the maximum elongation of Ni-Co alloy can reach the value of 279% at strain rate of 5× 10^-3 s^-1 and temperature 773 K, the maximum elongation ofNi/Si3N4（w） composite is 635% at strain rate of 1 × 10^-2 s^-1 and temperature 713 K. Scanning electron microscopy and transmission electron microscopy were employed to examine the microstructures of the as-deposited and deformed samples. The superplastic behavior of the alloy and composite were compared with and discussed in terms of their grain growth behavior and accommodation mechanisms.