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(一)表面渗氮的原理根据E.Leheser的铁氮合金平衡图,氨在加热的铁表面分解,生成“氮原子”。这种“氮原子”被铁表皮吸收,而产生特殊的氮扩散层。由于含氮量的不同,在不同温度下有下列四个安定相的存在(其中γ相仅在共析温度以上才呈平衡相存在)。 (1)固溶氮的α铁………α(体心立方格子), (2)固溶氮的γ铁………γ(面心立方格子), (3)固溶铁的Fe_4N………γ＇(面心立方格子), (4)固溶铁的Fe_2N ………ε(稠密立方格子)。
(A) surface nitriding principle According to E. Leheser’s iron-nitrogen alloy equilibrium diagram, ammonia in the heated iron surface decomposition, generating a “nitrogen atom.” This “nitrogen atom” is absorbed by the iron skins and produces a special nitrogen diffusion layer. Due to the different nitrogen contents, the following four stable phases are present at different temperatures (the γ phase is only present at equilibrium above the eutectoid temperature). (1) solid solution nitrogen of α-iron ......... α (body-centered cubic lattice), (2) solid-solution nitrogen of γ-iron ......... γ (face-centered cubic lattice), (3) ... γ ’(face-centered cubic lattice), (4) Fe 2 N ......... ε (dense cubic lattice) of solid-solution iron.