Hardening and phase stability in rapidly solidified Al-Fe-Ce alloys

Rapidly solidified (RS) Al-Fe-Ce alloys were prepared by melt spinning. The phases present and the thermal stability, at temperatures up to 500°C, were then followed by X-ray analysis, chemistry, hardness and thermal analysis techniques. The results obtained indicated that the alloys studied have enhanced mechanical properties compared to commercial aluminium alloys and castings of the same alloy compositions, and the RS alloy also exhibit good stability up to about 300°C; a result of stable second phase particles. It is suggested that these results indicate that there are two mechanisms responsible for the hardening and stability of the RS alloys: solid solution strengthening at lower temperatures, and semicoherent particles formed from supersaturated solid solution at higher temperature. The maximum hardness, after 2 h ageing occurred at about 300°C. At higher temperatures the dispersed phase became incoherent with a dramatic loss in hardness.