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<p>Hybrid aluminum metal matrix composites (HAMMCs) have garnered significant attention in modern engineering applications due to their superior properties and tailorable characteristics over single-phase AMMCs. Accordingly, this study focuses on the synergistic effect of micro-sized silicon carbide (SiC) and silicon nitride (Si<sub>3</sub>N<sub>4</sub>) particulates on microstructure-mechanical response of high-strength Al7075 aluminum alloy in as-cast and T6 heat-treated conditions. The Al7075/SiC/Si<sub>3</sub>N<sub>4</sub> composite was synthesized into samples S0 to S4 using the conventional stir casting route, ensuring homogeneous distribution of the reinforcements within the Al7075 matrix by varying the reinforcement levels of micro-sized particles. T6 heat treatment was also employed for precipitation-hardenable Al7075 and respective aging-response of samples was studied. Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS) and optical microscopy revealed significant variations in interfacial characteristics, elemental composition and dendritic morphology, respectively, across different compositions, while XRD analysis confirmed phase constitution with no undesirable phase formation. The composites tensile strength and hardness were measured using a universal testing machine (UTM) and a Rockwell hardness tester, respectively. The presence of Si<sub>3</sub>N<sub>4</sub> improved the overall tensile strength of the composite by inducing grain refinement and reducing crack propagation, while SiC significantly contributed to increased hardness and improved load transfer from soft matrix to reinforcement. The study revealed that sample S3 containing 0.5% SiC+2.5% Si<sub>3</sub>N<sub>4</sub> demonstrated optimal strength gains, recording 730 MPa in as-cast and 746&#xa0;MPa in heat-treated conditions, respectively, due to induced grain refinement and even particle dispersion, while heat-treated composites exhibited substantial increase in hardness due to precipitation strengthening mechanisms. This study builds a practical understanding of how reinforcement ratio influences composite performance and future work on wear and fatigue would further validate their potential in demanding structural applications.</p>

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Correlation Between Microstructural Refinement and Mechanical Performance in Al7075 Hybrid Composites Reinforced with SiC and Si3N4

  • 期刊论文

  • 发表日期：

    2026年4月12日

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  • Bhupesh Sahu,
  • M Dubey,
  • Rajan Kumar

摘要

Hybrid aluminum metal matrix composites (HAMMCs) have garnered significant attention in modern engineering applications due to their superior properties and tailorable characteristics over single-phase AMMCs. Accordingly, this study focuses on the synergistic effect of micro-sized silicon carbide (SiC) and silicon nitride (Si3N4) particulates on microstructure-mechanical response of high-strength Al7075 aluminum alloy in as-cast and T6 heat-treated conditions. The Al7075/SiC/Si3N4 composite was synthesized into samples S0 to S4 using the conventional stir casting route, ensuring homogeneous distribution of the reinforcements within the Al7075 matrix by varying the reinforcement levels of micro-sized particles. T6 heat treatment was also employed for precipitation-hardenable Al7075 and respective aging-response of samples was studied. Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS) and optical microscopy revealed significant variations in interfacial characteristics, elemental composition and dendritic morphology, respectively, across different compositions, while XRD analysis confirmed phase constitution with no undesirable phase formation. The composites tensile strength and hardness were measured using a universal testing machine (UTM) and a Rockwell hardness tester, respectively. The presence of Si3N4 improved the overall tensile strength of the composite by inducing grain refinement and reducing crack propagation, while SiC significantly contributed to increased hardness and improved load transfer from soft matrix to reinforcement. The study revealed that sample S3 containing 0.5% SiC+2.5% Si3N4 demonstrated optimal strength gains, recording 730 MPa in as-cast and 746 MPa in heat-treated conditions, respectively, due to induced grain refinement and even particle dispersion, while heat-treated composites exhibited substantial increase in hardness due to precipitation strengthening mechanisms. This study builds a practical understanding of how reinforcement ratio influences composite performance and future work on wear and fatigue would further validate their potential in demanding structural applications.