A peritectic phase refines the microstructure and enhances Zn implants

Abstract Zn has currently drawn great attention as potential orthopedic implant material due to its desirable biodegradability and good biocompatibility. In present study, Cu was introduced into Zn bone implant fabricated by laser powder bed fusion. Particularly, Cu dissolved in Zn liquid during melting, and subsequently partitioned ahead of the advancing liquid-solid interface during cooling. In this condition, a peritectic phase, ɛ-CuZn5, precipitated priority and acted as heterogeneous nucleation sites. It reacted with surrounding liquid phase to generate refined η-Zn grains, resulting in grain refinement and precipitation strengthening. As a result, the compressive yield strength, ultimate tensile strength and hardness were increased to 165 ± 7 MPa, 223 ± 4 MPa and 97 ± 2 HV, respectively. Moreover, Zn-Cu alloy exhibited a greatly enhanced antibacterial activity as compared with Zn, as the released Cu ion could damage cell membrane structure and inhibit plasmid/DNA replication. Furthermore, it also presented favorable biocompatibility as well as suitable degradation rate. It was demonstrated that Zn-Cu alloy may be a promising candidate as bone implant.