Microstuctures of Al-Cr alloys containing Cr up to 10% solidified by various cooling methods and precipitation behavior during aging at 200-600°C of a melt spun Al-2.75%Cr alloy were investigated. No precipitates can be observed in splat quenched Al-10%Cr nor in melt spun Al-2.75% alloys. The hardness of chill cast alloys increases with Cr content up to about 4%. Electrical resistivity of the melt spun 2.75% Cr alloy shows a two stage sigmoidal recovery during isothermal aging at 200-600°C. Electron microscopy observation of aged samples concludes that the first and the second stages of electrical resistivity change correspond to preferred precipitaion at grain boundaries and within grains, respectively. The size R, half of the length, and S, thickness of the grain boundary precipitated particles during isothermal aging are proportional to tn, where t is isothermal aging time. The time dependent exponent n for R and S are 0.077-0.083 and 0.11-0.17, respectively.
