Effect of heat treatment on corrosion and wear properties of powder metal AZ91 magnesium alloy

Abstract Magnesium alloys are promising for lightweight structural applications but are limited by poor wear and corrosion resistance. This study investigates the combined effects of compaction pressure and heat treatment on the microstructure, wear, and corrosion behavior of powder metallurgy AZ91 alloy. Samples compacted at 200–300 MPa underwent T4, T5, and T6 heat treatments. A maximum relative density of 98.67 % was achieved at 300 MPa. Pin-on-disc and electrochemical tests revealed a strong inverse relationship between wear and corrosion resistance. T6-treated samples showed the highest wear resistance, reducing wear loss by ∼50 % compared to as-fabricated specimens, due to fine β-Mg 17 Al 12 precipitates enhancing hardness and tribofilm formation. However, this microstructure led to severe corrosion (67.71 mm y −1 ). In contrast, T5 and T4 treatments improved corrosion resistance (11.41 and 12.89 mm y −1 ) by minimizing micro-galvanic coupling but offered moderate wear resistance. These results highlight that a single heat treatment cannot optimize both properties, underscoring the need for application-specific processing strategies.