The reinforcement of an age-hardenable Al–Cr matrix alloy in situ and by SiC/Al2O3 particles: tailoring of the interface

Al–Cr alloys containing less than 0.75% Cr give rise to an age-hardening effect and the alloys also exhibited a good combination of strength and ductility properties. The achievable high toughness of these alloys led to an attempt to produce in situ composites with an Al–Cr solid solution as the matrix phase and excess insoluble intermetallics of chromium aluminides as the reinforcing constituent. The development of composites based on the Al–Cr matrix alloy with SiC and/or Al2O3 as the reinforcing phase was also attempted by a casting route. It was observed that the increase in strength was quite considerable even with a relatively good ductility. The precipitation behaviour and its kinetics in this newly developed composite were also studied by differential scanning calorimetry (DSC) and transmission electron microscopy (TEM).