Diffusion of lanthanum in nanocrystallized surface layer during plasma rare earth nitriding of 3J33B steel
(黑龙江省哈尔滨市哈尔滨工业大学材料科学与工程学院)
Abstract: Plasma rare earth nitriding of nanocrystallized surface layer of 3J33B steel at 350 and 410℃ for different time was studied. The microstructure observation and X-ray diffraction（XRD） analysis show that the nitriding layer consists of compound layer （γ′-Fe4N） and diffusion layer （α-Fe）. Lanthanum content profiles in nanocrystallized surface layer were measured using glow discharge spectometry（GDS）. The results show that lanthanum can diffuse into the surface layer of the steel to a large depth. Based on the experimental results mentioned above, the diffusion coefficients and activation energy of lanthanum in γ′ phase are calculated to be 1.03×10 -15 cm2/s （350℃）, 1.75×10-15 cm2/s （410℃） and 31.313kJ/mol, respectively.
Key words: 3J33 steel； nanocrystallized surface layer； plasma nitriding； lanthanum； diffusion