Low temperature and high strain rate superplasticity of Ni-1 mass%SiC nanocomposite

The superplastic deformation behaviour of a Ni-1 mass%SiC nanocomposite produced by pulse electrodeposition was investigated at temperatures of 410°C and 450°C and strain rates ranging from 8.3 × 10-4to 5.0 × 10-2s-1. A maximum elongation of 836% was obtained at 450°C and a strain rate of 1.67 × 10-2s-1, which is the first observed result of the high strain rate and low temperature superplasticity for Ni-SiC nanocomposites. Scanning electron microscopy and transmission electron microscopy were employed to examine the microstructure of the as deposited and deformed samples. The superplastic behaviour of the Ni-1%SiC nanocomposite was analysed through observations of its fracture surfaces and microstructures. The results showed that SiC nanoparticles play an important role in the stability of the microstructure of the Ni-SiC nanocomposite. A low volume fraction of cavity is necessary for a large elongation. The mechanisms of high strain rate and low temperature superplasticity of the composite are discussed in the paper.