Development of Ductile Cr-Re Alloys for High Temperature Application in Aggressive Atmosphere

Abstract

Mechanical properties, oxidation and thermal shock resistance of Cr-Re solid solution alloys manufactured by arc melting have been characterized. Samples of pure Cr, Cr-18at%Re and Cr-35at%Re alloys have been tested at temperatures up to 1400°C for compression resistance. Oxidation resistance of the alloys has been tested up to 1600°C in air and thermal shock resistance at heating kinetics of 500°C/s and 500°C/mm has been investigated. Results confirm the potential of near solid solution limit Cr-Re alloys as high temperature materials for operation in aggressive atmosphere. In as cast condition Cr-35at%Re alloys present a room temperature compressive yield stress of 900 MPa and show relatively good ductility (6%) under tension. Yield stress under compression at 1400°C is 168 MPa and 140 MPa under tension at 1200°C. 4 hours exposure to air at 1600°C produced a metal recession of about 15μm and a diffusion layer of 50μm. Thermal shock of the alloys under the conditions described above produced small cracks on the surface. Further work will include the determination of the alloy resistance to pure nitrogen at high temperature and the measurement of the thermal properties and thermal expansion coefficients of the alloys.Key wordsRefractory alloysrhenium effectCr-Re alloysmechanical propertieshigh temperatureoxidation resistancethermal shock resistance