Laser additive manufacturing of Zn-2Al part for bone repair: Formability, microstructure and properties

Zinc (Zn) alloys are promising bone repair materials due to their inherent degradability, favorable mechanical property and biocompatibility. In this investigation, laser powder bed fusion (LPBF) known as a representative additive manufacturing technique was applied to fabricate Zn-2Al (wt.%) part for bone repair application. A low energy density (Ev) led to the formation of pores and resultant insufficient densification rate due to the high liquid viscosity within the molten pool. In contrast, a high Ev caused the evaporation of Zn powder and resultant failure of LPBF. With Ev increasing, the obtained grains and the precipitated lamellar eutectic structure contained η-Zn and α-Al phase became coarsened, which could be attributed to the enhanced heat accumulation and consequently decreased cooling rate. At optimized Ev of 114.28 J/mm3, fully dense Zn-2Al part with a densification rate of 98.3 ± 1.4% was achieved, which exhibited an optimal hardness of 64.5 ± 1.8 Hv, tensile strength of 192.2 ± 5.4 MPa and a moderate corrosion rate of 0.14 mm/year. In addition, in vitro cell tests confirmed its good biocompability. This study indicated that LPBF processed Zn-2Al part was a potential material for bone repair. •Zn-2Al part is successfully built using laser additive manufacturing process.•High densification rate and fine microstructure is achieved at optimized Ev.•It exhibits superior mechanical properties and suitable degradation rate.