The effect of compaction pressure for on properties of binary and ternary magnesium alloys

The aim of this work was to investigate the effect of compaction pressure on the densification, and mechanical properties of binary and ternary Mg-based alloys that have potential to be used as biodegradable implant metals. The mixture of Mg-10wt%Zn and Mg-9wt%Zn-lwt%Mn alloy were mechanically alloyed (MA) in a planetary ball mill. The as-milled powder was consolidated by compacting the powder into 10mm diameter pellet with compaction pressure varied from 100-600MPa followed by sintering at 300°C for 1 hour. The effect of compaction pressure on microstructure was investigated by x-ray diffraction measurement (XRD) and optical microscope (OM) while densification of the sample determined by Archimedes density measurement. Mechanical properties of the sample was investigated by microhardness and compression test. The result show that a homogenous supersaturated solid solution of Mg-10wt%Zn and Mg-9wt%Zn-lwt%Mn was obtained after 2 hours of milling time. The density of the alloy was increased with increasing compaction pressure up to 400MPa before decrease with further increase of compaction pressure. Significant enhancement of hardness and compressive strength were observed in Mg-9wt%Zn-lwt%Mn alloy (72.9 Hv, 255MPa) compared to Mg-10wt%Zn alloy (66.9Hv, 245MPa). The ternary Mg-based alloy of Mg-9wt%Zn-lwt%Mn provide better mechanical properties than binary Mg-alloy of Mg-10wt%Zn. The compaction pressure of 400MPa was the optimum case for preparing such Mg-alloy and further increase of the pressure led to deterioration of mechanical properties of the alloy.