稀土元素有很低的电负性和高的化学活性,与N、H、O可能发生强烈的化学反应,其加入可促进高分子的键链破坏,促使氨和乙醇的热分解更加完全,生成较多的[N]、[C]原子,活化炉气,从而强化其氮碳共渗的动力学过程。稀土元素的原子半径远大于铁,只能渗入球墨铸铁表面的薄微区,并优先占据石墨边界、晶界、位错等原子排列紊乱的晶体缺陷处。稀土元素的渗入同时造成周围铁素体的点阵畸变,增加空位缺陷,使间隙原子[N]、[C]易于进入其八面体间隙位置,由于代位稀土原子与周围氮、碳原子的交互作 Rare earth elements have low electronegativity and high chemical activity, and N, H, O may occur a strong chemical reaction, the addition can promote the destruction of the bond chain of the polymer, ammonia and ethanol to promote the thermal decomposition more completely, to generate More [N], [C] atoms, activation furnace gas, thereby strengthening its nitrocarburizing kinetics. The atomic radius of rare earth elements is much larger than that of iron, which can only penetrate into the thin micro-areas on the surface of ductile iron, and preferentially occupy the crystal defects with disordered atoms such as graphite boundaries, grain boundaries and dislocations. Rare earth element infiltration at the same time cause the surrounding ferrite lattice distortion, increase vacancy defects, so that interstitial atoms [N], [C] easy to enter the octahedral interstitial position, due to the substitution of rare earth atoms with the surrounding nitrogen, carbon atoms interaction