Exploiting the mechanical properties and optimising wear characteristics of Mg–Al–Zn hybrid composites reinforced with Si3N4 and MoS2

The advancement of lightweight structural materials with enhanced wear resistance continues to be a significant problem for magnesium-based alloys exploited in engineering applications. This research investigates the constraints of mechanical integrity and subpar tribological performance in Mg-Al-Zn alloys by integrating Si₃N₄ and MoS₂ hybrid reinforcements through a powder metallurgy approach. The effect of reinforcement content on density, hardness, and compressive strength was assessed, and wear behaviour was optimised through a Taguchi L9 orthogonal array to determine the main variables influencing the tribological responses. Three different trials (1-3) were used to analyse the mechanical properties with varied processing parameters, and its microstructure and mechanical properties were analysed as per ASTM standards. The microstructure observation revealed that trial 1 (Mg-Al-Zn alloy + 2 wt% Si₃N₄ + 2 wt% MoS₂) and trial 2 (Mg-Al-Zn alloy + 4 wt% Si₃N₄ + 2 wt% MoS₂) showed Si₃N₄ and MoS₂ particles agglomerating in the Mg alloy due to lower surface energy, while trial 3 (6 wt% of Si₃N₄, 2 wt% of MoS₂) exhibited a refined grain structure and acted as nucleation sites for grain refinement during sintering. SEM morphology inferred that the ceramic particles are uniformly distributed in trial 3 comprising of MoS₂, 510 °C of sintering temperature, 2.5 h soaking time, 550 MPa compaction pressure, improving mechanical properties such as hardness (43.47 ± 0.1%), compressive strength (51.16 ± 0.2%), and corrosion resistance (30.86 ± 0.01%) compared to trials 2, 3, and the Mg-Al-Zn alloy. XRDA confirms that due to higher sintering temperatures, Mg alloy interacts with ceramic particles to form the Mg₂Si, Mg₃N₂ interface. The intermixture's enhanced particle diffusion and bonding resulted in improved corrosion resistance. ANOVA analysis confirmed that Trial 3 confirmed that applied load significantly influences wear rate and CoF, with a contribution exceeding 90% and p < 0.05 in CoF analysis, followed by sliding speed and distance.