Influence of HPT on mechanical properties and corrosion behavior of Mg-1Zn alloy

Abstract

This paper examines a binary magnesium alloy, Mg–Zn, which is considered as a biodegradablemedical implant material. Particular attention is paid to its mechanical and corrosion properties. Theeffect of high pressure torsion (HPT) and annealing on the corrosion rate and strength of the Mg–1Znalloy is analyzed. The homogenized condition, a HPT sample, and a condition after HPT followedby heat treatment at 300 °C, which provides an optimal combination of strength and ductility, wereselected for testing. It was found that homogenized samples exhibit the highest corrosion resistance(0.7 mm/year) due to the absence of secondary phases that create galvanic couples with the matrix.After HPT, the corrosion rate increases to 2.1 mm/year, while subsequent heat treatment leads to itsdecrease to 1.2 mm/year. Metallographic studies confirmed that the surface of homogenized samplesexhibited greater corrosion resistance, while severe corrosion pits formed on the surface after HPT.The HPT + 300 °C heat treatment exhibited intermediate corrosion resistance, as well as increasedstrength (198 MPa) and ductility (24%), compared to the initial homogenized condition, which hada strength of 138 MPa and ductility of 12%.