Influence of high temperature oxidation on mechanical properties and in vitro biocompatibility of WE43 magnesium alloy fabricated by laser powder bed fusion

Laser powder bed fusion (L-PBF) has been used to fabricate biodegradable Mg implants of WE43 alloy, but the degradation is too fast compared with the term bone reconstruction. Previous studies show that high temperature oxidation (HTO) can successfully inhibit the degradation of WE43 alloy. In this work, the influence of HTO on L-PBF samples of WE43 alloy was investigated regarding tensile, compressive, and abrasive resistance, as well as in vitro cytotoxicity, cell proliferation, hemolysis, and osteogenesis. Compared with the as-built L-PBF samples, HTO increased grain size and grain texture, stabilized and coarsened precipitates, and caused discontinuous static recrystallization in the matrix. The oxide layer at the surface of the HTO samples improved surface roughness, hydrophilia, hardness, and abrasive resistance. The tensile strength decreased slightly from 292 to 265 MPa, while the elongation substantially increased from 10.97% to 16.58% after HTO. The in vitro cell viability, cell proliferation, hemolysis, and osteogenic effect were considerably enhanced due to the improvement of surface quality and the initial inhibition of excessive Mg2+ releasement. Overall, HTO is of great benefit to the surface performance, ductility, and biocompatibility of WE43 alloy fabricated by L-PBF for biodegradable applications.