钇对17CrMoV钢离子氮化特性的影响及催渗机理的探讨

The Influence of Yttrium on the Plasma Nitriding Characteristics of 17CrMoV Steel and its Mechanism

本研究采用金相显微镜、透射电子显微镜、显微硬度计等仪器分析对比了１７ＣｒＭｏＶＹ和１７ＣｒＭｏＶ钢离子氮化层特性，探讨了钇加速离子氮化的机理，提出了钢中钇催渗的“气团─通道”模型。研究结果表明：钇显著提高渗层深度与硬度；钇影响钢的组织转变，提高渗层氮浓度，使氮化物更易于析出；大量弥散、细小氮化物的快速析出又为氮的进一步扩散提供了更多的扩散通道，加快氮的扩散。

The characteristics of plasma nitrided 17CrMoV and 17CrMoVY were observed and analysed by using optical, electron microscopy and Vickers' micro hardness testing. The mechanisms by which the. yttrium enhances the rate of the process were discussed. An atomic model based on electron affinity was proposed. The results show that yttrium significantly makes the treated case deeper and harder, influences the structure transformation in steel, raises the nitrogen content in the nitrided case, and makes the nitride precipitate more easy and speedy. The rapid precipitation of a large amount of fine and dispersive nitride provides more short paths for the diffusion of nitrogen atoms and makes nitrogen atoms diffusion faster.