Superplasticity and texture of SiC whiskers in a magnesium-based composite

Superplastic deformation behaviors in a β-SiCw/ZK60 composite were investigated. The samples were tested at temperatures ranging from 613 to 723 K and at initial strain rates ranging from 8.3 × 10−4 to 8.3 × 10−2 s−1. A maximum elongation of 200% was obtained at 613 K and at 1.67 × 10−2 s−1 with a m-value of 0.35. The activation energy (98 kJ/mol) approximates to that for grain boundary diffusion (92 KJ/mol) in magnesium. A strong 〈 1 1 1 〉 fiber texture was formed in SiC whiskers during superplastic deformation, resulting from the matrix flow and interface sliding. The alignment of SiC whiskers restrains the grain boundary sliding of matrix alloy, and thus facilitates the growth and linkage of cavities, leading to a premature fracture of the composite.