Synergistic effects of boron carbide and niobium reinforcements on the mechanical performance of Al-8090 alloys

Abstract

This experimental study investigates the impact of boron carbide (B _4 C) and Niobium (Nb) reinforcement particles on the microstructural, mechanical and surface properties of Al-8090 base alloy. The inclusion of B _4 C and Nb particles significantly refines the structure which enhances the properties via nucleation and dispersion strengthening effects. Optical microstructures and Scanning Electron Microscopy images show that an increase in reinforcement percentages precedes finer grains and uniform particle distribution. Energy Dispersive x-ray Spectroscopy analysis highlights a predominant aluminium (Al) peak in the Al-8B _4 C-5 Nb sample and Nb and Fe minor peaks indicate potential diffusion interaction. Mechanical tests reveal substantial improvements in hardness, tensile strength, and density of the Al-7B _4 C-3 Nb sample obtained the highest values. However, increasing reinforcement content causes agglomeration which declines the hardness and increases porosity. The wear test demonstrates that the reinforced composites perform superior properties, with B _4 C providing surface layer protection and Nb refining the grain structure. Corrosion analysis reveals that inclusion reinforcements act as initiation sites for intergranular and localized corrosion due to the galvanic interaction effect. These findings recommend that an optimized reinforcement content in Al-8090 base alloy yields better mechanical performance and wear resistance for high-strength applications.

Keywords

• Al-8090 alloy
• B4C and Nb reinforcements
• stir casting
• microstructure
• mechanical properties