High creep resistance of titanium aluminides sintered by SPS

Abstract

Reducing fuel consumption, noise, and greenhouse gas emission of airplanes engines requires to use lighter materials. Titanium Aluminides (TiAl) are of great interest to be employed for high temperature applications like turbine blades as they are twice lighter than superalloys currently used. A few years ago, two engines produced by GENERAL ELECTRIC and SNECMA-SAFRAN including TiAl turbine blades have been certified. However, TiAl alloys still suffer from a poor ductility at room temperature, a difficult and expensive manufacturing process, and a limited creep resistance at working temperature. We adapted the Spark Plasma Sintering, a powder metallurgy technique, to produce near-net shape turbine blades with an optimized TiAl alloy containing heavy elements to enhance the creep resistance. In this paper, we will present a study of creep properties under extreme conditions such as 700 °C/300 MPa of TiAl alloys, sintered by SPS, able to resist more than 4000 h with a minimum creep rate of 3.5 × 10-9 s-1. These outstanding properties will be correlated with microstructure features, chemistry, and deformation mechanisms.