Effect of alloy composition and reinforcement with silicon carbide on the microstructure and mechanical properties of three silicide dispersion strengthened aluminium alloys

Two rapidly solidified and mechanically milled Al–Mn–Si alloys and one Al–Fe–V–Si alloy were consolidated both in monolithic form and as-reinforced with 20 wt.%SiC particulate (SiCp). The microstructure of the alloys has been determined using transmission electron microscopy (TEM) and Vickers hardness has been measured in the as-forged condition, after heat treatment for 100 h at 550°C and after heat treatment for up to 3100 h at 425°C (the latter for unreinforced alloys only). The heat treatments at 550°C were used to investigate the formation of Al13Fe4 in the Al–Fe–V–Si alloys. Elevated temperature properties of the alloys have been investigated by comparing the tensile mechanical properties at 20°C and 350°C for all alloys. The significance of these results for microstructural stability at elevated temperatures, operating strengthening mechanisms and the effects of SiCp reinforcement in such alloy systems, are discussed.