Effects of Aluminizing on Tensile Property and High-Temperature Oxidation of TiAl-base Alloys

Abstract

The influence of aluminizing treatment on oxidation resistance at 1173K in the atmosphere and on room temperature ductility of TiAl based alloys with a good room temperature ductility has been examined. The quaternary alloys containing of 2mol%Nb, Ti-48 Al-2Nb-2Cr and Ti-48Al-2Nb-2Mn, show better oxidation resistance than Ti-50Al binary alloy and/or Ti-47Al-2Cr-0.2Si quaternary alloy. An aluminizing treatment of 1173K×18ks forms an coating layer of the TiAl₃ phase of approximately 30μm in thickness. The coating layer facilitates the formation of the Al₂O₃ phase in the initial stage of oxidation. The aluminizing treatment improves the oxidation resistance of the binary and quaternary alloys, irrespective of their composition. The quaternary alloys with aluminizing treatment have better room temperature elongation than the Ti-50Al with or without the aluminizing treatment, though room temperature ductility of all the alloys used decreases with the aluminizing treatment.
It has been concluded that the aluminizing treatment for quaternary alloys of Ti-48Al-2Nb-2Mn and Ti-47Al-2Cr-0.2Si is beneficial to application of these alloys under the oxidizing atmospherical circumstances at high temperature of 1173K.