Abstract
The low-pressure-plasma spray (LPPS) process is used to overlay coatings of MCrAlY alloy for protection against high temperature corrosion and oxidation. This coating process has been found to be very effective for gas turbine components. However, mechanical properties of LPPS MCrAlY alloy, which have an important effect on coating life, have not always been clarified. Five kinds of freestanding MCrAlY specimens (CoCrAlY, CoNiCrAlY, CoNiCrAlY+Ta, NiCrAlY, NiCoCrAlY) were machined from the thick LPPS coatings. Also, the heat treated MCrAlY specimens (1393K, 2h, Ar atmosphere) were used in experiments. The Vickers hardness, Young's modulus, Poisson's ratio and four point bending strength of the LPPS MCrAlY alloy were measured at room temperature in comparison with a nickel-base super-alloy, IN738LC. The experimental results suggest that the volume percentage of precipitated aluminum composite in the LPPS MCrAlY alloy has an important effect on the mechanical properties. Namely, there is a tendency that the Vickers hardness and Young's modulus increase with increasing the volume percentage of aluminum composite, and conversely the bending strength decreases with increasing the volume percentage of aluminum composite.
