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研究了气体渗氮层和激光淬火/渗氮层的N分布、微观结构、显微硬度及脆性。结果表明,激光淬火后的组织晶粒细小,晶界和位错、孪晶等缺陷数量增加,而N在晶界和缺陷处扩散激活能降低,使N的扩散速度和扩散通量提高,渗氮层厚度增加;同时渗氮层晶粒细小致密,细小的高硬度的Cr2N颗粒数目增加,使显微硬度值显著提高,渗氮层脆断的临界压力由气体渗氮层的3 N提高到激光淬火/渗氮层的6 N。
The nitrogen distribution, microstructure, microhardness and brittleness of gas nitrided layer and laser quenched / nitrided layer were studied. The results show that after laser quenching, the grain size of the microstructure is small, the number of defects such as grain boundaries and dislocations and twins increases, while the diffusion activation energy of N decreases at the grain boundaries and defects, increasing the diffusion rate and diffusion flux of N, While the thickness of nitrogen layer increases. At the same time, the number of fine and compact high-hardness Cr2N grains in the nitrided layer increases and the microhardness value increases remarkably. The critical pressure of nitrided layer brittle fracture is increased from 3 N of gas nitrided layer to 6 N of laser quenched / nitrided layer.