Influence of silicon nitride (Si₃N₄) reinforcement on mechanical properties and wear behaviour of AZ31–Nano alumina (Al₂O₃) composites developed through the stir casting route

In this study, hybrid composites consisting of AZ31 alloy matrix reinforced with 2 wt% aluminum oxide nanoparticles (Al 2 O 3 ) and 2, 4, or 6 wt% silicon nitride microparticles (Si 3 N 4 ) have been prepared using the stir casting route. The mechanical properties, such as hardness, tensile strength, compression strength, impact strength, and sliding wear performance, were evaluated for the fabricated hybrid composites. The mechanical properties improve significantly with the inclusion of reinforcement content. The hybrid composite having 4 wt% Si 3 N 4 reinforcement exhibits higher mechanical properties like micro-hardness (68.8 HV), tensile strength (172 MPa), percentage of elongation (11.9%), compression strength (278 MPa), and impact strength (6.4 J). The wear rate and coefficient of friction tend to reduce with the inclusion of Si 3 N 4 reinforcement content under dry sliding wear conditions. Worn-out surface micrograph investigation displays wear mechanisms such as abrasive wear and plastic deformation with micro–ploughing and micro-cutting.