Effect of Ll2(Al,Cr)3Ti film on high temperature oxidation behavior and mechanical properties of TiAl

摘要

The oxidation behaviors and the mechanicalproperties of TiAl alloys coated with the Al-21Ti-23Cr and the Al-21Ti-23Cr-0.1Y films were investigated. A small addition ofyttrium to the coating material was effective in the improvementof the oxidation resistance of the Ti-48Al. From the scratch test,specimen coated with the Al-21Ti-23Cr-0.1Y film had betteradhesion between the Al2O3 scale and the coating layer than onecoated with the Al-21Ti-23Cr film. And AFM study showed thatthe Al2O3 surface of the Al-21Ti-23Cr-0.1Y coating is moresmooth than one of the Al-21Ti-23Cr coating after isothermaloxidation. Thus, it is suggested that this excellent oxidationresistance is attributable to the excellent adhesion between theAl2O3 scale and the Al-21Ti-23Cr-0.1Y film and the smoothAl2O3 surface of the Al-21Ti-23Cr coating after isothermaloxidation. Thus, it is suggested that this excellent oxidationresistance is attributable to the excellent adhesion between theAl2O3 scale and the Al-21Ti-23Cr-0.1Y film and the smoothAl2O3 surface of the Al-21Ti-23Cr-0.1Y coating. From thetensile test, it was found that Al-21Ti-23Cr-0.1Y coating enablesthe TiAl to maintain more effectively its tensile properties in anoxidizing environment than the Al-21Ti-23Cr coating. Moreover,the specimen coated with the Al-21Ti-23Cr-0.1Y film showedlower creep rate and longer time to rupture than the specimenwithout coating, under the constant stress of 200 Mpa at 1123K inair. Therefore, it could be assumed that the Al-21Ti-23Cr-0.1Yalloy was prospective as an oxidation-resistant coating material forTiAl alloys.