8High strength and high ductility combination of biodegradable high-purity magnesium fabricated by forward extrusion and extrusion-shear process

Abstract

High-purity magnesium has been increasingly investigated as a biodegradable metal due to its excellent biocompatibility and unique biodegradability. However, its inadequate mechanical properties remain a critical bottleneck to its application. In order to improve its strength and ductility, forward extrusion (FE) and extrusion-shear (ES) were performed on the high-purity magnesium. The impact of the FE and ES process on the microstructure, texture, and mechanical properties of the material was examined. The results indicate that the grain size of high-purity magnesium was refined from 40.1 μm to 12.7 μm and 2.8 μm, and the yield strength was increased from 75.2 MPa to 101.2 MPa and 148.8 MPa after the FE and ES. The tensile elongation to failure of high-purity magnesium decreases sharply from 10.9% to 3.3% after the FE, while the tensile elongation to failure after ES increases significantly to 18.3%. A stronger basal texture was observed after the FE, while a weaker basal texture and a more dispersed recrystallization texture were produced by the ES process. The contribution of grain size, dislocation density and texture to the yield strength of high purity magnesium after different extrusion processes was calculated, and the results were in good agreement with the experiments. This shows that the improvement in yield strength is primarily attributed to grain refinement, while ductility was enhanced by the weakening of the basal texture.