Thermal stability of electrodeposited nanocrystalline Ni-45%Fe alloys

Electrolytically deposited nanocrystalline Ni-45%Fe alloys, composed of gamma (f.c.c.) phase, were annealed at 573 and 673 K for time periods up to 20 h in an inert atmosphere of argon. The evolutions of crystallographic texture, grain size, and microhardness were analyzed as a function of annealing parameters. The initial grains, approximately 5 nm in size increased after annealing up to 10-20 nm, however, the growth kinetics and the finaI grain size depended on the temperature. A correlation was found between the grain size and alloy microhardness. The phase composition was unstable and during annealing the alpha(b.c.c.) phase was detected to precipitate from the gamma matrix. The texture of gamma phase, consisted of two fibre components of [111] and [200], and evolved at high temperatures. Although the detailed changes depended on the annealing temperature, in general, the [111] component became stronger at the expense of the [200] component.