A partially degradable composite consisting of Ti-Zr-Cu-Pd-Sn metallic glass and Fe-Mg alloy for orthopedic applications

Abstract

Partially-degradable biomaterials refers to smart implants where biodegradable metals can gradually be replaced by newly growing bone or living tissues, and leave behind a porous inert metal skeleton that stably binds with the new bone tissue. In this research, a partially degradable composite was designed by integrating Ti-Zr-Cu-Pd-Sn metallic glass (MG) with designed Fe-Mg alloy using spark plasma sintering (SPS). The mechanical alloying technique successfully enabled the fusion of immiscible Fe and Mg, addressing the issues of Fe's slow degradation and Mg's rapid breakdown, while also minimizing potential fractures in the metal framework due to hydrogen gas evolution. The controlled degradation of Mg(Fe) promotes the formation of Ca-P compounds, enhancing the bioactivity of the Fe-Mg composite. This design endows the composite with plastic and ductile deformation under compression, providing a viable solution to the brittle fracture behaviour commonly associated with conventional bulk metallic glasses (BMGs). This advancement holds promise for aligning with the natural growth rate of human bone, further augmenting the bioactive properties and practical applications of the MG/Fe-Mg composite material.

Statement of significance

In this research, a partially degradable composite was designed by integrating Ti-Zr-Cu-Pd-Sn metallic glass (MG) with designed Fe-Mg alloy using SPS. The Fe-Mg alloy act as temporary space holders can gradually being replaced by newly formed bone, thus establishing a dynamic equilibrium between the biodegradation of the bio-metals and the inward growth of new bone. The degradation of Mg(Fe) promotes the formation of Ca-P compounds, enhancing the bioactivity of the composite. This design endows the composite with plastic deformation under compression, providing a viable solution to the brittle fracture behavior of conventional MGs. This advancement holds promise for aligning with the natural growth rate of human bone, further augmenting the practical applications of the MG/Fe-Mg composite.