Effect of passivation and precipitation hardening on processing and mechanical properties of B4C–Al composites

Boron carbide–aluminium composites were produced by infiltrating aluminium alloys into porous boron carbide preforms at different temperatures under an argon gas atmosphere. Aim of this study was controlling the reaction between starting constituents by the use of various heat treatments. In order to reduce consumption of the starting constituents (B4C and Al) due to formation of reaction products, a thermal passivation process was employed to the as-received B4C powders, which facilitates easier and faster infiltration of liquid Al into the porous compacts at temperatures as low as 900 °C. The Al constituent of the composites was then subjected to a precipitation hardening heat treatment to further improve their bending and compressive strength. This heat treatment was observed to result in a remarkable increase in both the bending and compressive strengths of the composites.