The intermetallic compound (48at%Al) was bombarded with 200keV He ions at 623 or 773K. The He-cavity density decreased with decreasing α2 and γ lamellar width. A plot of cavity density versus lamellar width yielded a linear relationship after irradiation to 15dpa. The cavity density in regions with 300nm-wide lamellae was about half of that in large γ-grains. The α2/γ lamellar boundaries were a preferred nucleation site for cavities. Although cavities also formed at the γ/γ lamellar boundaries, nucleation was limited to misfit dislocations on the boundaries. Defect-free zones were found in regions, some 50nm-wide, which were immediately adjacent to the lamellar boundaries at 773K. It was concluded that lamellar boundaries were effective sinks for radiation defects, and contributed to the suppression of radiation-induced defect-cluster development.

Role of α2/γ and γ/γ Phase Boundaries in Cavity Formation in a TiAl Intermetallic Compound Irradiated with He Ions. K.Nakata, K.Fukai, A.Hishinuma, K.Ameyama: Journal of Nuclear Materials, 2000, 283-287, 278-81