Exploring the microstructural and mechanical response of aluminum composites reinforced with SiN: A novel hybrid microwave sintering approach

¹ K. S. R. M Colleges of Engineering, Department of Mechanical Engineering, Kadapa- 516003, India
² Annamacharya Institute of Technology and Sciences, Department of Mechanical Engineering, Rajampet, Andhra Pradesh, 516126, India
³ Department of Mechanical Engineering, Jawaharlal Nehru Technological University Anantapur, Ananthapuramu, India

^* Corresponding author: pullaiahphd@gmail.com

Published online: 7 January 2026

Abstract

This study investigates the microstructural and mechanical behavior of AA7075 aluminum matrix composites reinforced with varying weight percentages (1–8 wt%) of silicon nitride (SiN), processed via high- energy ball milling and hybrid microwave sintering. Microstructural characterization revealed uniform SiN dispersion and strong matrix–particle interfaces up to 6 wt%, while higher loadings led to agglomeration. Mechanical testing demonstrated significant improvements in tensile strength (149 MPa), compressive strength (237 MPa), and hardness (107 HV) at 6 wt% SiN, attributed to Orowan looping, load transfer, grain refinement, and Zener pinning mechanisms. Beyond this threshold, reinforcement agglomeration adversely affected performance. The results confirm that hybrid microwave sintering is a viable and energy-efficient route for producing high-strength aluminum-based composites, with 6 wt% SiN identified as the optimum reinforcement level.