Flow stress of rapidly solidified Al-5Cr-2Zr alloy as a function of processing variables

The highest flow stress of gas atomised and extruded Al-5Cr-2Zr alloy in the test temperature range of 373 to 773 K was obtained for specimens processed from the smallest powder particle size extruded at the lowest temperature. As test temperature increased the beneficial effect of small powder particle diameter increasingly prevailed over that of low extrusion temperature. The major microstructural feature that contributed to the high flow stress of the Al-5Cr-2Zr alloy was the small grain size. At low test temperatures, the Hall-Petch strengthening mechanism accounted for as much as 90% of the yield strength. At high test temperatures, although degradation occurred, some strengthening still persisted up to at least 773 K.