Superplasticity of nanostructured nickel alloy and composite fabricated by electrodeposition

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 of Ni/ 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.