Ion implantation and thermal oxidation

Explanatory research has been performed to examine surface modification by ion implantation as a method to improve the oxidation and hot corrosion resistance ofa typical high temperature alloy. Polished surfaces of IN939 nickel-base alloy were implanted with platinum in a high energy ion-implanter. The ion-implanted and unimplanted coupons were oxidized at 9500C in the slowly flowing air at 1 atm. A Cahn microbalance was used to document the weight gains. A few cyclic oxidation tests were also carried out. Surface and bulk microstructures were characterized by SEM, EDAX and TEM before and after the high temperature exposure. The study demonstrted improvement in the scale adherence under cyclic oxidation but not in the isothermal oxidation resistance. This observation appears to be the first showing improved chromia scale adherence in nickel-base alloys due to the presence of Pt. (orig.)