Controllable degradation behavior of Mg-Sr-Y alloys for the bio-applications

Abstract

The biodegradation behavior and mechanical properties of Mg-Sr-Y alloys were systematically investigated for the medical application. The alloy (Mg-0.3Sr-0.5Y) exhibits a comparable UTS as 111.53 MPa and shows a general uniform degradation behavior with low corrosion rate as only 0.823 mm y⁻¹ in Hanks’ solution. The simultaneous solid solution of Y in α-Mg phase and in Mg₁₇Sr₂ phase reduces the micro-galvanic corrosion. Additionally, the formation of a compact composite film of Mg(OH)₂, Y₂O₃ and Sr-substituted phosphate (Sr-HA) delivers the protection for the matrix. Low corrosion rate, fine precipitates and dispersed Y rich-zones, which hinder the corrosion propagation, further guarantees a uniform degradation behavior. While, with increasing Sr content, the corrosion resistance is deteriorated because of the formed continuous distribution of Mg₁₇Sr₂ along grain boundaries. By tailoring composition and structure, Mg-Sr-Y alloys with balanced mechanical and bio-degradation properties can be promising for the bio-applications.