A 5th generation Ni-base single crystal superalloy designed for the combination of excellent oxidation resistance and creep strength at elevated temperatures

Abstract

The National Institute of Materials Science (NIMS) has utilized the in-house alloy design program to develop a 5 th generation Ni-base single crystal superalloy, TMS-196 with superior high temperature creep and oxidation resistance by incorporating further ruthenium (Ru) and chromium (Cr) content over the compositions of 4 th generation superalloys. With Ru additions in advanced superalloys to enhance phase stability, higher content of refractory elements can be accommodated to provide further strengthening; the associated oxidation resistance can be improved by the increase in Cr additions. In present article, TMS-196 has been subjected to cyclic/isothermal oxidation tests at 1100°C and creep at conditions between 800°C-1100°C/137 MPa-735 MPa. Preliminary studies indicate that the surface of oxidized TMS-196 can exhibit continuous alumina layer attributing good oxidation resistance similar to that of Rene'N5. Detailed TEM analyses have shown the alloy system of TMS-196 possessing strong resistance to γ′ deformation during creep deformation. Data regarding to oxidation and creep properties of some previous generations of superalloys are also included for comparisons and discussions in this research. © 2006 The Japan Institute of Metals.