Effect of heat treatment on wear properties of extruded AZ91 alloy treated with yttrium

The influence of heat treatment (T6) on the ambient temperature dry sliding wear behavior of the extruded AZ91 alloy treated with Y using a pin-on-disc apparatus was investigated. Wear rates and friction coefficients were measured within a load range of 5–70 N at a sliding speed of 0.188 m/s over a constant sliding distance of 226.195 m. Worn surfaces and debris were examined using a scanning electron microscope equipped with an energy dispersive spectrometer. The experimental results revealed that, as applied load was increased, the alloy wear rates increased, but the friction coefficients decreased. Four chief operating wear mechanisms were observed, i.e., abrasion, oxidation, delamination and plastic deformation. The extruded AZ91 alloy treated with Y exhibited better wear resistance by adopting T6, which was mainly due to large amounts of fine Mg17Al12 distributed in the grains and the resulting modified strength and micro-hardness.

Graphical AbstractWear rates of the tested alloys under different applied loadsFigure optionsDownload full-size imageDownload as PowerPoint slide