Oxidation Resistance of Ion-Implanted γ -TiAl-Base Intermetallics

Abstract

A series of alloy elements, including the detrimental, neutral, and beneficial elements for bulk alloying into gamma -TiAl base intermetallics, i.e., V, Cr, Y, Er, Nb, and W, has been implanted into a gamma -Ti-50Al intermetallic in order to explore the mechanism of high-temperature oxidation resistance for the ion-implanted intermetallic. The oxidation resistance was investigated under cyclic-oxidation conditions at oxidation temperatures from 800 to 1000degreesC for 200 hr in air. At a lower oxidation temperature of 800degreesC, the V-ion implantation has a detrimental effect on the oxidation resistance of Ti-50Al, while a neutral and beneficial effect was observed for Er-, Y- and Cr-, Nb-, W-ion implantation, respectively. At 900degreesC, V-, Er-, Y-, and Cr-ion implantation all showed a neutral effect, whereas Nb- and W-ion implantation apparently improved the oxidation resistance. With increasing oxidation temperature to 1000degreesC, Y- and Cr-ion implantation kept the neutral effect, and the beneficial effect of Nb-ion implantation disappeared gradually. The oxidation behavior of ion-implanted gamma -TiAl base intermetallics is different from that of bulk-alloyed materials due to the two alloying methods, although the effect of the alloy elements on the oxidation resistance has not essentially changed in the gamma -TiAl base intermetallics.