Tensile microstrain properties of vapour quenched and rolled Al-alloys

Abstract

Al-alloy deposits produced by quenching from the vapour phase were rolled into sheet and tensile stress-strain curves were obtained in the microstrain region (<10⁻⁴ strain). Two binary alloys (Al-5% Cr and Al-11% Cr) and two ternary alloys (Al-8% Cr-1.2% Fe and Al-6% Cr-1.0% Fe) were tested (compositions in wt%). The corresponding tensile strengths were 375 and 590 MPa for the binary alloys, and 679 and 662 MPa for the ternary alloys. The microyield stresses (the stress to produce a residual plastic strain of 2×10⁻⁶) for the vapour quenched alloys were less than 26 MPa compared with 100 to 260 MPa for commercial aluminium alloys. When the vapour quenched alloys were retested immediately after prestrain, the values were much greater (166 to 254 MPa), but after resting at room temperature for 7 to 106 days low values were again obtained. The low microyield stresses were attributed to the high density of dislocations present in the rolled sheet and the behaviour observed may be characteristic of high strength dispersion hardened Al-alloys produced by rapid solidification and rolling.