Biodegradable AZ31-calcium silicate composites produced by the solid-state method: assessing the corrosion-initiated mechanical failure

AZ31 Magnesium (Mg) alloy was incorporated with calcium silicate powder by friction stir processing (FSP), and the corrosion-initiated mechanical failure was investigated. FSPed AZ31 alloy without adding calcium silicate was also produced. X-ray diffraction studies demonstrated the development of basal dominated texture in the FSPed alloy and the composite. The average grain size was measured as 114 ± 5.8 µm for the starting material, 6.2 ± 2.5 µm for the FSPed alloy, and 3.5 ± 1.4 µm for the composite. From the electrochemical studies, a lower corrosion current density was observed for the FSPed AZ31 and the composite. The increased corrosion resistance is claimed to the positive role of refined microstructure and the addition of calcium silicate in AZ31 alloy. The surface morphologies after the corrosion test revealed more degraded regions with deeper pits on AZ31 alloy compared with FSPed AZ31 and the composite. Tensile tests carried out after subjecting the test samples to corrosion in 3.5% NaCl solution for 24 h demonstrated higher strength for the composites. From the results, it is concluded that producing AZ31-calcium silicate composites by FSP is a promising strategy in developing Mg-based degradable implants with improved mechanical performance in the presence of degraded regions.