ZnMg0.8Ca/Sr0.2 ternary alloys - the influence of the third element on material properties

摘要

Zinc-based materials alloyed with the elements of the 2nd group of the periodic table have been studied as potential materials for the fabrication of various biodegradable implants. In this study, we prepared two ternary alloys: ZnMg0.8Ca0.2 (wt.%) and ZnMg0.8Sr0.2 by melting a mixture of pure elements and subsequent gravity casting. We studied the influence of the third element (Ca or Sr) on the micro structural and mechanical characteristics of the alloys in the as-cast states and after various times of annealing at 350°C. The micro structure of both ternary alloys was similar, the main difference was in the size and morphology of the Ca/SrZn_(13) phase. The SrZn_(13) phase formed fine particles with a submicron size and had more significant hardening effect in the as-cast state compared to the CaZn_(13) phase. The annealing led to a transformation of the eutectic structure into the "massive" Mg_2Zn_(11) phase which caused a significant increase of both hardness and compressive yield stress. In the annealed states, comparable hardness was observed for both alloys and higher compressive yield strength for the Ca-containing alloy.