Metal matrix composites based on valence-unstable systems

Abstract

Abstract The work is focused on the thermal expansion of composites based on valence-unstable systems. The main motivation was to create invar-like materials of a new type and to develop approaches to the quantitative description of coefficients of thermal expansion (CTE) of both the composite itself and its key component - a material with a negative contribution to thermal expansion due to valence fluctuations. The experimental data on the linear CTE of Al/SmB6 composite was performed by capacitive dilatometry in the temperature range 5-220K. It turned out that this composite shows invar properties up to 60K. Several models were used to describe thermal expansion in Al/SmB6. A quantitative approach is proposed for describing the negative magnetic contribution and the lattice contribution to the CTE of systems based on intermediate-valence samarium hexaboride.