Effect of Low Additions of Y, Sm, Gd, Hf and Er on the Structure and Hardness of Alloy Al – 0.2% Zr – 0.1% Sc

Abstract

The structure and phase composition of addition alloys based on aluminum with Hf, Er, Gd, Yand Sm and the effect of low additions of these transition metals on the structure and properties of alloy Al – 0.2% Zr – 0.1% Sc are studied. It is shown that individual introduction of Y, Sm, Er, and Gd in an amount of 0.1% each causes formation of eutectic phases Al₃Y, Al₃Sm, Al₃Er and Al₃Gd, respectively. An indirect inference is that the additions of Y, Sm, Hf, Er and Gd raise the thermal stability of the Al₃ (Sc, Zr) dispersoids after annealing at 250°C with a hold of up to 100 h; softening at 370°C starts after holding for 54 h. Maximum hardening is detected in the case of 0.1% Er and attains 50 HV after a 54-h hold at 370°C.