Effect of Yb on the Structure and Properties of an Electroconductive Al–Y–Sc Alloy

Abstract

The influence of ytterbium addition on the phase composition, strengthening upon annealing before and after rolling, and on the electrical conductivity and mechanical properties of the Al–0.2% Y–0.2Sc alloy has been investigated in this work. A dispersed eutectic, in which particles of an intermetallic phase with a size of 100–250 nm are enriched in yttrium and ytterbium, has been revealed in the cast structure apart from the aluminum solid solution. The maximum strengthening of the ingot is achieved after the annealing at 300°C for 3 hours due to the precipitation of Al3M dispersoids. The annealing of deformed sheets at 300°C results in an increase in the hardness and yield strength, which is connected with the initiation of the process of the additional decomposition of the aluminum solid solution. This means that the addition of ytterbium stimulates the heterogeneous nucleation of Al3M dispersoids in the post-rolling annealing process. In this case, according to the international standard for the annealed copper, the electrical conductivity increases with increasing temperature and time of annealing from 54 to 54.9% and to 57.7% after annealing at 200°C and 300°C, respectively.