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

摘要

Several rapidly solidified (RS) Al-base systems for high temperature applications have been studied in recent years (1), among which are those based on the Al-Cr-Zr family of alloys where the'AluCft phase provides thermal stability and the metastable LI 2-AijZr phase provides age hardening (2). By rapid solidification, however, non-massive products are typical, e.g. powder particles by gas atomisa-tion. The as-atomised microstructure is strongly linked to the powder particle diameter so that small powder particles present higher supersaturation of the solid solution, smaller grain/subgrain sizes and smaller precipitate sizes than large powder particles (3). A consolidation step, i.e. a thermomechanical processing such as direct extrusion (4), should always follow the production of the rapidly solidified (RS) Al alloy powder for high temperature applications. Consolidation variables play a crucial role in their final mechanical behaviour, as they can considerably modify the original RS microstructure (5).