Microstructural evolution, mechanical properties, and corrosion resistance of a heat-treated Mg alloy for the bio-medical application

During the recent years, some Mg based alloys have extensively been considered as a new generation of degradable and absorbable bio-medical materials. In this work, the Mg-2Zn-1Gd-1Ca (wt%) alloy as a new metallic bio-material was produced by the casting process followed by the heat treatment. The samples of the alloy were solution treated at temperatures of 500, 550, and 600 degrees C and then quench aged at temperatures of 125, 150, and 175 degrees C. The results of SEM-EDS examinations indicated that the alloy microstructure consists of alpha-Mg matrix and the Ca2Mg6Zn3 and Mg3Gd2Zn3 secondary phases. With regard to the results of Vickers hardness test, the temperatures of 500 degrees C and 150 degrees C were selected as the optimum solutionizing and aging temperatures, respectively. Moreover, the dissolution of casting precipitates and production of lattice distortion occurring after the solution treatment led to the reduction in ultimate shear strength up to 21%. But, the precipitation hardening and morphological changes taking place during the aging treatment improved the ultimate shear strength up to 32%. Furthermore, the results of electro-chemical and weight-loss measurements in a simulated body fluid indicated that the heat-treated alloy is a promising candidate for the Mg based alloys recently considered for the bio-medical applications. (C) 2018 Published by Elsevier B.V. on behalf of Chongqing University.