用滴注式气渗法对工业纯铁施行低温碳氮和稀土碳氮共渗对比实验，发现在６００℃，４ｈ条件下，稀土碳氮共渗试样由表及里出现硬度和碳浓度的“双峰效应”据此，提出共渗稀土优先沿晶界扩散的通道模型并对“双峰效应”进行了半定量计算，得出：在实验条件下强制固溶于铁的稀土的固溶量 By drip infiltration method of industrial pure iron to carry out low-temperature carbonitriding and rare earth carbonitriding contrast experiments found at 600 ℃, 4h conditions, rare earth carbonitriding samples from the table and the hardness and carbon concentration “Bimodal Effect” Based on this, we propose a channel model for preferential diffusion of rare earth along the grain boundary and semi-quantitatively calculate the “bimodal effect”. The results show that the solution of rare earth Solubility 