Abstract
The current study has investigated the influence of zirconium (Zr) addition to Mg-3Ca-xZr (x = 0.3, 0.6, 0.9 wt%) alloys prepared using argon arc melting on the microstructure and impression properties at 448-498 K under constant stress of 380 MPa. Microstructural analysis of as-cast Mg-3Ca-xZr alloys showed grain refinement with Zr addition. The observed grain refinement was attributed to the growth restriction effect of Zr in hypoperitectic Mg-3Ca-0.3 wt% Zr alloys. Heterogeneous nucleation of alpha-Mg in properitectic Zr during solidification resulted in grain refinement of hyperperitectic Mg-3Ca-0.6 wt% Zr and Mg-3Ca-0.9 wt% Zr alloys. The hardness of Mg-3Ca-xZr alloys increased as the amount of Zr increased due to grain refinement and solid solution strengthening of alpha-Mg by Zr. Creep resistance of Mg-3Ca-xZr alloys increased with the addition of Zr due to solid solution strengthening of alpha-Mg by Zr. The calculated activation energy (Q(a)) for Mg-3Ca samples (131.49 kJ/mol) was the highest among all alloy compositions. The Q(a) values for 0.3, 0.6 and 0.9 wt% Zr containing Mg-3Ca alloys were 107.22, 118.18 and 115.24 kJ/mol, respectively.