The microstructure, mechanical properties and degradation behavior of laser-melted MgSn alloys

Mg is a potentially biomaterial for bone implant due to its biodegradability and biomechanical compatibility. However, the too fast degradation rate limits its clinical application. In the study, both alloying treatment and laser rapid melting were applied to slow down its degradation rate. The microstructure, mechanical properties and degradation behavior of the MgxSn (x = 0-7 wt %) alloys were investigated. With Sn content increasing, the grain sizes decreased, while the new Mg2Sn phase increased. The refined grain slowed the degradation rate due to the reduced segregation. While the Mg2Sn phase accelerated the degradation rate owing to the couple galvanic corrosion. Thus, the optimal degradation behavior was obtained with a balanced grain size and Mg2Sn phase volume fraction. Besides, the compression strength increased firstly (up to 5 wt %) and then decreased with Sn increasing.