Preparing high-strength and osteogenesis-induced Mg-Gd alloy with ultra-fine microstructure by equal channel angular pressing

Mechanical strength and corrosion resistance are needed for Mg based BMs in the application of biomedical fields. In the present study, a high-strength biodegradable Mg-Gd alloys with an ultrafine microstructure successfully were prepared by equal channel angular pressing (ECAP). The high tensile strength of ECAPed Mg-Gd alloys was attributed to ultrafine DRX grains and fragmented secondary phases. During ECAP, the grain structure was refined by dynamic recrystallization (DRX), and the size of the DRX grains was approximately 300 nm. The secondary phase with lamellar structures was fragmented into fine particles of submicrometer size after ECAP process. As the number of ECAP passes increased, the distribution of the fragmented secondary phase has been changed into a uniform distribution. The corrosion rates calculated from the hydrogen evolution test demonstrated that the 8p-ECAP Mg-Gd alloy with an ultrafine microstructure possessed better corrosion resistance. Cell and osteogenesis induction experiments confirmed that Mg-Gd alloys processed by ECAP exhibited good biocompatibility. This study provides a new method for preparing high-strength Mg alloys with good corrosion resistance and biocompatibility.