Development of AlCrX and AlCrZrX alloys by rapid solidification from the melt

Abstract

The development of novel aluminium-based engineering alloys with substantial additions of chromium, zirconium and/or manganese by rapid solidification (RS) takes advantage of the ready susceptibility to extension of solid solubility and lowered diffusivities in α-Al of these additions compared with, for example, those of iron, cobalt or nickel. The present contribution is concerned with the investigation of some alternatives to X ≡ Zr in AlCrX and to X ≡ Mn in AlCrZrX systems developed earlier, particular attention being given to the refractory metals X ≡ Nd, Mo, Hf and W. The level of retained microhardness after exposure for up to 1000 h at 673 K of splats made by the twin piston technique of RS of levitation-melted alloy samples was used as an initial indication of the thermal stability of such alloys. Especially promising results were obtained for X ≡ Hf in AlCrX and X ≡ W and Nb in AlCrX, the behaviour of which is compared with AlCrZr and developmental AlCrZrMn, AlFeCe and AlFeMo alloys for the same exposures.