Structure and mechanical properties of rapidly solidified Al-Cu alloys

Abstract

Al-4, 10 and 25mass%Cu alloy ribbons were produced by a rapid solidification method using a single roller technique. Cooling rates were estimated to be about 10⁴-10⁶K/s. The microstructures, differential scanning calormetry, tensile strength/yield stress and hardness of the ribbons were investigated. The structures of cross-section of ribbons were composed of fine crystalline grains, fine dendrites and non-equilibrium celluar eutectic structures formed in coupled zone. The precipitation in the rapidly solidified ribbons started at lower temperatures and was observed at a wider temperature range than that in the solution treated alloys. This was explained by the increased dislocation density and grain boundary area in rapidly solidified ribbons. The maximum tensile strength and yield stress were obtained in the alloys annealed at about 400-500K. The microstructure and hardness of the chilled surface were different from those of the free surface. The increased annealing temperature resulted in the similar values of hardness in both surfaces of ribbons.