Dual phase formation in multilayered Ni-Al by ion beam mixing

Abstract

Ion beam mixing is used to homogenize multilayered thin films of nickel and aluminum, vapor deposited onto pure nickel substrates. Doses of 500-keV Kr+ at fluences of 2×1016 ions/cm2 produced a supersaturated solid solution of between 16 and 23 at. % aluminum in nickel at room temperature. Subsequent thermal treatment at 425 °C for 1 h resulted in the formation of a dual phase structure of γ and γ′ with grain sizes in the range 640 to 710 Å. Although the dual phase structure was obtained either by ion beam mixing followed by thermal annealing or by thermal annealing alone, only the former process resulted in a surface film with a texture. The films are stable against thermally induced grain growth at temperatures up to 700 °C for 10 h.