Platinum-Containing New Generation Nickel-Based Superalloy for Single Crystalline Applications

Abstract

TROPEA, a new platinum-containing single crystal (SX) superalloy, has been developed for high-temperature components of aircraft engines. Criteria used for the alloy design procedure to target specifications are presented. TROPEA properties have been characterized and compared to reference alloys. First casting showed good castability of the alloy with no tendency to freckles formation. TROPEA exhibits excellent yield stress up to 800 °C compared to second- or third-generation SX superalloys and resistance above 800 °C similar to second-generation superalloys. This new alloy shows high low cycle and very high-cycle fatigue properties, particularly at low temperature. TROPEA exhibits high creep resistance at temperatures above 1200 °C, stable microstructure (no TCP phases) with a density (8.83 g.cm−3) intermediate to that of second- and third-generation SX superalloys. Atome probe tomography measurements show that platinum preferentially partitions to γ′ precipitates. Platinum additions significantly stabilize γ′ phase near solvus temperature and consequently increase alloys properties at (very) high temperature despite a low rhenium content. Thus, platinum emerges as a promising element to enhance high-temperature properties of SX superalloys in addition to or as an alternative to rhenium. The high creep properties at very high temperature combined with excellent fatigue properties at low temperature make TROPEA a promising SX superalloy for highly cooled turbine components.