稀土元素对渗硼动力学的影响

Effect of rare earth element on boronization kinetics

采用固体渗硼法对45钢和T12钢在1053～1213K分别进行单一渗硼和添加Nd2O3稀土渗硼。分析了稀土元素对渗硼动力学的影响。结果表明:稀土元素的加入有助于渗硼层中Fe2B相的形成,提高渗层中Fe2B相所占比例,改善渗层组织和性能。同时,加入稀土能够使硼的扩散系数增大,使扩散激活能降低,45钢中硼的激活能由184kJ/mol降到122kJ/mol,T12中硼的激活能由261kJ/mol降到155kJ/mol,分别降低了34%和41%,显著提高了渗硼速率。根据所得数据建立了45钢在添加w(Nd2O3)=5%稀土渗硼时的渗硼层等厚线图。

Steels 45 and T12 were boronized using a plain boride agent and a series of Nd2O3-containing boride agents in a temperature range of 1053-1213 K to obtain the single-borided and rare earch（RE）- borided layers. The effect of the RE on the boronization kinetics was analyzed. The results show that addition of RE accelerates formation of Fe2B phase, consequently increases the fraction of FeeB phase in boride layer, improves its microstructure and performance. RE increases the diffusion coefficient and decreases the diffusion activation energy of the boron atom： from 184 to 122 kJ/mol for steel 45 and from 261 to 155 kJ/mol for steel T12,i.e, it is reduced by 34% and 41% respectively, enhancing effectively the boronizing rate. The contour diagram of the boride layer thickness of the steel 45 boronized with 5% Nd2O3 addition was built according to experimental data.