The presence of Cu-rich nanoprecipitates in a pearlitic spheroidal graphite (ductile) cast iron alloyed with 0.82 wt%Cu was studied. The size and distribution of the precipitates were examined by transmission electron microscopy at different locations of the pearlitic matrix. Some areas were nearly free from precipitates, while other regions showed precipitates at the cementite and ferrite lamellae and at the ferrite/cementite interface. Calculation of the thermodynamic equilibrium under stable and metastable conditions using Thermo-Calc led to the identification of the conditions controlling the formation of Cu-rich nanoprecipitates along three different stages depending on the Cu concentration. Together with a differential scanning calorimetry test and elemental diffusional calculations, thermodynamic predictions supported the observation of Cu-rich precipitates despite the low concentration of Cu of the alloy investigated and allowed the authors to explain the observed heterogeneity in the distribution of precipitates as resulting from the heterogeneous distribution of Cu in the alloy caused by microsegregation during solidification. The knowledge gained is relevant for the design of strengthening strategies in SGI based on the dispersion of Cu-rich nanoprecipitates.

研究了与0.82 wt％Cu合金化的珠光体球形石墨（延性）铸铁中富Cu纳米沉淀的存在。通过透射电子显微镜在珠光体基质的不同位置检查沉淀物的尺寸和分布。一些区域几乎没有沉淀物，而其他区域在渗碳体和铁素体薄片以及铁素体/胶凝体界面处显示出沉淀物。使用Thermo-Calc计算在稳定和亚稳态条件下的热力学平衡导致确定了根据Cu浓度控制在三个不同阶段控制富Cu纳米沉淀形成的条件。连同差示扫描量热法测试和元素扩散计算，尽管所研究的合金中铜的浓度较低，但热力学预测仍支持观察富铜沉淀物，并允许作者解释由于凝固过程中微观偏析导致合金中铜的不均匀分布而导致的沉淀物中分布的不均匀性。 。所获得的知识与基于富含铜的纳米沉淀物分散的SGI强化策略设计有关。