Microstructure and tensile properties of 5A90 Al–Mg–Li alloy containing minor Sc cast by low-frequency electromagnetic casting

Abstract

The effects of low-frequency electromagnetic casting (LFEC) on the microstructure and tensile properties of 5A90 Al–Mg–Li alloy with and without minor Sc were investigated. In addition to minor Sc, the refined microstructures of the conventional direct chill cast (DCC) alloy and the microstructures of the as-cast alloy were refined further and more equiaxed grains formed in LFEC ingots with Sc. Higher density, smaller size, and more uniform distribution Al3(Sc, Zr) in the aged alloy with Sc induced by LFEC, which pins on grain boundaries, can effectively inhibit recrystallization. As a result, it had been a significant improvement in strength which was mainly due to the Orowan effect of Al3(Sc, Zr) dispersoids combined with grain refinement. The ultimate tensile strength of 565.4 MPa, yield strength of 475.3 MPa, and the corresponding elongation of 6.4% were obtained in the as-aged 5A90 alloy with 0.15 wt% Sc cast by LFEC at 10 Hz and 100 A.