Ferrous scraps have been widely utilized as raw materials in the production of ductile irons. With increasing scrap use and repeated recycling, the concentrations of tramp elements such as copper (Cu) and tin (Sn) in the raw materials are expected to increase as they cannot be easily removed through conventional refining processes. To obtain fundamental insights into the effects of high-concentration Cu (up to 2.0 wt pct) and Sn (up to 1.0 wt pct) on the nucleation and growth of graphite on a foreign substrate, a novel approach through contact-melting of cast iron on lanthanum oxide (La₂O₃) substrate is utilized to study graphite nucleation and growth behavior at the alloy/substrate interface and in the bulk alloy. Enhanced graphitization at the alloy/substrate interface and in the bulk alloy are observed at varying Cu content. Copper promotes graphitization in cast iron by elevating the equilibrium liquidus temperature of graphite (T_G) and increasing the carbon supersaturation (ΔC). On the other hand, Sn demonstrates stronger graphitizing effects than Cu as only a lower concentration of Sn is required to achieve a similar increase of T_G and ΔC. More significantly, Sn enhances graphite nodule counts in the bulk alloy through the formation of fine La-Sn intermetallic compounds which act as effective sites for graphite nucleation.

亚铁废料已被广泛用作生产球墨铸铁的原料。随着废料用量的增加和重复回收的使用，原料中诸如铜（Cu）和锡（Sn）等流浪元素的浓度预计会增加，因为它们无法通过常规精炼工艺轻易去除。要获得对高浓度铜（最高2.0 wt pct）和锡（最高1.0 wt pct）对异质基底上石墨成核和生长的影响的基本认识，这是一种通过铸铁接触熔化的新颖方法在氧化镧上（La ₂ O ₃）基底用于研究合金/基底界面以及块状合金中的石墨成核和生长行为。在不同的铜含量下，在合金/基体界面和块状合金中的石墨化增强。铜通过提高石墨（的平衡液相线温度促进铸铁石墨化Ť _ģ）和增加碳的过饱和（Δ Ç）。另一方面，Sn表现出比Cu更强的石墨化效果，因为仅需较低浓度的Sn即可实现T _G和ΔC的相似增加。 更重要的是，Sn通过形成细小的La-Sn金属间化合物而增强了块状合金中的石墨结核数量，这些化合物是石墨成核的有效部位。