Fabrication and Mechanical Characterization of Al-Li 2050 Alloy Metal Matrix Nanocomposites Reinforced with Nano-Alumina (Al₂O₃) via Stir Casting

Abstract

This investigation reports the synthesis and mechanical characterisation of Al-Li 2050 aluminium alloy matrix nanocomposites reinforced with 13 nm α-Al₂O₃ particles at weight fractions of 0, 0.5, 1.0, and 1.5 wt.%, fabricated via the stir-casting (liquid metallurgy) route. A two-step homogenisation treatment (500 °C/10 h + 515 °C/20 h, heating rate 180 °C/h, air-cooled) was applied prior to mechanical evaluation. Specimens were assessed for ultimate tensile strength (UTS), yield strength (YS), percentage elongation, Brinell hardness (BHN), and apparent density. UTS increased monotonically from 121.62 N/mm² (unreinforced) to 138.04 N/mm² at 1.5 wt.% Al₂O₃ (+13.5%), while BHN improved from 54.30 to 61.43. Percentage elongation and density declined with increasing reinforcement content, consistent with particle-constraint effects. Results confirm the viability of the Al-Li 2050/Al₂O₃ system for lightweight structural applications.