Superplastic behavior of fine-grained extruded ZK61 Mg alloy

Abstract

The superplasticity of a fine-grained extruded ZK61 magnesium (Mg) alloy was investigated by tensile testing at various elevated temperatures and strain rates. The results demonstrated the strain rate sensitivity (m-value) ~0.51 and ~0.4 and stress exponent (n-value) ~1.96 and ~2.5 at temperatures 673 K and 623 K, respectively. The numerical simulation revealed that the activation energy (Q-value) was in the range of 92.9–146.7 kJ/mol. Therefore, the high elongation to fracture (FE) ~400% and ~334% were achieved at temperatures 673 K and 623 K under tensile loading at a strain rate of 0.001 s−1. The microstructure was thermally stable at elevated temperatures and attributed to MgZn2 phase particles. Based on m-value, n-value, FE, average Q-value ~114 kJ/mol, and thermally stable microstructure, it was found that the governing deformation mechanism was the intra-granular slip. These all feathers assisted in understanding the superplastic behavior of the ZK61 Mg alloy.

Keywords

• Fine-grain
• Extrusion
• Tensile
• Superplastic behavior
• MgZn2