Effect of chip size on mechanical property and microstructure of AZ91D magnesium alloy prepared by solid state recycling

In this study, different kinds of AZ91D magnesium alloy chips were prepared by solid state recycling. Mechanical properties and microstructures of the recycled specimens were investigated. Various microstructural analyses were performed using the techniques of optical microscopy, scanning electron microscopy and oxygen-nitrogen analysis. Microstructural observations revealed that all the recycled specimens consisted of fine grains due to dynamic recrystallization. The oxide precipitate content is closely related to the recycled chip size. Accumulated oxygen concentration linearly increases with the total surface area of the machined chips in the recycled specimens. Ambient oxide in the recycled specimen contributes to a higher ultimate tensile strength and a higher elongation to failure; however, excessive oxide in the recycled specimen may adversely affect the elongation to failure.