Processing, Microstructure, and Thermal Expansion Measurements for High Temperature Ru-Al-Cr B2 Alloys

Abstract

AbstractThe B2 intermetallic compound RuAl has a melting temperature above 2000 °C and is a candidate for high temperature structural applications. A large extension of the B2 phase field is found in the Ru-Al-Cr system as was documented by the characterization of arc-melted and heat treated alloys. Two compositions consisting of Ru-35Al-19Cr and Ru-20Al-38Cr (at. %) were directionally solidified in an optical floating zone furnace. Depending upon the processing conditions, single phase, polycrystalline, B2 microstructures could be produced. The coefficient of thermal expansion (CTE) was measured from room temperature to 1250 °C for the Ru-20Al-38Cr alloy, and an average value of 11×10-6 K-1 was found. Additionally, the thermal conductivity was measured as 27 W/mK at room temperature for the Ru-20Al-38Cr B2 alloy and as 89 W/mK for binary RuAl.