Microstructural and mechanical characterization of AA2124 aluminum alloy matrix composites reinforced with Si₃N₄ particulates fabricated by powder metallurgy and high-energy ball milling

The study aims to enhance the mechanical properties of AA2124 aluminum alloy matrix composites reinforced with silicon nitride (Si₃N₄) particulates, utilizing powder metallurgy and high-energy ball milling techniques. Reinforcing metal matrices with ceramic particulates like Si₃N₄ offers potential strength, hardness, and thermal stability improvements for advanced engineering applications. AA2124 alloy powder was mixed with Si₃N₄ particulates (5-20 wt%) and milled for varying durations to achieve uniform dispersion. The mixtures were compacted and sintered at 500°C in an argon atmosphere. Microstructural characterization was performed using SEM, XRD, and particle size analysis. Mechanical properties were evaluated through tensile, fatigue, and creep tests, along with microhardness measurements. The composites exhibited significant improvements in mechanical properties, with optimal results observed at 15 wt% Si₃N₄ and 60 minutes of milling. The tensile strength increased to 475 MPa from 320 MPa, and microhardness reached 297 kgf/mm² compared to 37 kgf/mm² for the unreinforced alloy. Enhanced fatigue life and creep resistance were also noted. This study demonstrates that optimizing Si₃N₄ content and milling duration can significantly enhance the mechanical properties of AA2124 composites, making them suitable for aerospace and other high-performance applications. The findings provide a basis for developing advanced aluminum matrix composites with superior mechanical properties. (author)