Hardness of ion-implanted Ni3Al and TiAl

Abstract

Experiments were conducted to determine the effect of various implanted species on the hardness of single crystal Ni3Al (Ta, Al, B) and polycrystalline TiAl (Ta, N, B). Implantations were conducted to yield about 7 at. % Ta under the peak and ∼30% Al, N, or B under the peak in the respective targets. Hardness was measured using the Nanoindenter. Results showed that Ta+-implanted Ni3Al softens due to disordering, and subsequent heat treating results in strengthening due to preferential occupation of Al lattice sites. However, B+ and Al+ implantations result in increases in the hardness, while heat treating returns the surface hardness to bulk values. Ta+, N+, and B+ implantations into TiAl all result in hardening with N+ implantation producing the greatest hardening by a factor of ∼1.9. The probable mechanism is solid solution strengthening.