抄録
The nitriding of Fe–V alloys in NH3 atmosphere results in the formation of a subscale with rather high hardness values. The hardness of this subscale shows a gradual change to that of the unnitrided ferrite matrix especially in low vanadium containing alloys such as those that contain 1.06%V . The formation of such a hardness transition region is explained in terms of the increase in precipitate density with time, which in turn is the result of the high solubility of VN precipitates in ferrite. The experimental data indicate that the precipitation process starts with the formation of coherent precipitates which then grow in size and become incoherent upon further annealing. The formation of the coherent precipitates with extra nitrogen atoms results in the expansion of ferrite lattice.
