High Temperature Micromechanical Behavior of a Pt-Modified Nickel Aluminide Bond-Coating and of Its Interdiffusion Zone with the Superalloy Substrate

摘要

The micromechanical properties of a beta-(Ni,Pt)Al bond-coating was investigated between 700 degrees C and 1000 degrees C using ultrathin freestanding bond-coating specimens. Its brittle-to-ductile transition temperature was close to 750 degrees C, with a significant ductility above 800 degrees C (up to 23 pct at 1000 degrees C). The tensile strength decreased from 450 MPa at 750 degrees Cdown to 50 MPa at 1000 degrees C. Fractographic observations evidenced the material brittleness at intermediate temperature with large cleaved grains and its ductility above 750 degrees C with important necking of individual grains.