Long-Term Creep and Oxidation Behavior of a Laves Phase-Strengthened NiAl-Ta-Cr Alloy for Gas Turbine Applications

摘要

A Laves phase strengthened NiAl-Ta-Cr alloy (IP 75) has been developed for structural applications in gas turbines as well as in heat exchangers. It has a lower density and a higher thermal conductivity as well as a higher melting point than conventional superalloys. Different methods for alloy production have been established including investment casting (IC) and a powder metallurgical method (PM). Creep properties have been determined in compression and tension. Tension tests up to 10000 hours were performed at 900 deg C and 1000 deg C for both PM and IC materials. The oxidation behavior of the PM and IC material was studied for up to 1000 hours by thermogravimetry in air at constant temperature between 600 deg C and 1300 deg C. The results are compared with results obtained from long-term isothermal and cyclic oxidation experiments in air at 1200 deg C for 17900 hours. Microstructures and scales were examined by light optical and scanning microscopy, X-ray powder diffraction and electron probe microanalysis.