Abstract

The effect of nickel on the solubility of Fe4N and the diffusion of nitrogen in α-iron was examined by an internal friction technique. The used materials were pure iron and iron alloys containing 0.5, 1.0, 2.1 and 4.7 wt% nickel. The experimental results are as follows:(1) During measuring the Snoek peak of internal friction, it is necessary to apply the magnetic field of more than about 80 Oe to the specimen in order to eliminate the magnetoelastic damping.(2) The Snoek peak due to nitrogen in iron-nickel alloys takes place by the single relaxation mechanism.(3) The diffusion of nitrogen in α solid solution of iron and iron-nickel alloys was examined in the frequency range from 0.5 to 2.0 cps. Consequently, the diffusion coefficent of nitrogen in these alloys is represented by D=2.2×10−3exp(−18000⁄RT) and the effect of nickel on diffusion is negligible.(4) The solubility of Fe4N in α-iron is given by the equation log(N%)=−1230⁄T+0.36, and the heat of solution of Fe4N for α-iron is about 5600 cal/mol. The increase of nickel content dissolved in α solid solution has an effect of decreasing the solubility of Fe4N and has an effect of increasing the heat of solution of Fe4N.

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