Enhanced low-temperature superplasticity of Ni-Co alloy by addition of nano-Si₃Ni₄ particles

In this paper, the low-temperature superplasticity of the electrodeposited Si3N4/Ni-Co nanocomposite was investigated for the first time at temperatures ranging from 673 to 823 K and at constant strain rates from 1 × 10-3 to 1 × 10-2 s-1. A maximum elongation of 692% was obtained at a temperature of 723 K and a strain rate of 5 × 10-3 s-1. High-strain rate superplasticity with an elongation of 371% was realized at a temperature of 723 K. It was found that the Si3N4 nanoparticles play an important role in the stability of the microstructure of the Si3N4/Ni-Co nanocomposite. The relatively large superplasticity of the nanocomposite compared to the Ni-Co alloy is discussed. Deformed microstructure, fracture and surface morphology are examined and the deformation mechanism of the composite is discussed.