High temperature strength of Pt-base superalloys with different γ′ volume fractions

Pt-Al-Cr-Ni alloys with various γ′ volume fractions were investigated in terms of microstructure and compression strength at high temperature. In contrast to Ni-base superalloys, strengthening beyond the rule of mixture due to coherent γ/γ′ interfaces decreases with increasing temperature. Constrained and unconstrained lattice misfits were determined by high temperature X-ray diffraction analyses on the isolated γ and γ′ phases and on an alloy with about 50 vol.% γ′.