ABSTRACT

The precipitation of carbides at grain boundaries in nickel-based superalloys and austenitic stainless steels can significantly affect the grain boundary related properties of the bulk material. This study evaluated the growth and dissolution of carbides in grain boundary engineering (GBE) treated nickel-based superalloy (Inconel 690) during aging treatment using scanning electron microscopy and transmission electron microscopy. The grain boundary network was stable during aging below 1000°C. At lower aging temperatures of 715 and 800°C, a small number of tiny carbide precipitates were observed on Σ3_c grain boundaries. In contrast, plate-like carbides precipitated near both sides of Σ3_i grain boundary and on one side of Σ9 grain boundary, and large carbide precipitates formed on Σ27 and random grain boundaries. At higher aging temperatures of 900 and 1000 °C, large carbide precipitates with a more consistent morphology precipitated at Σ9, Σ27, and random grain boundaries. Carbide dissolution was common during aging at these higher temperatures, which promoted the growth and redistribution of other carbides. These experimental findings provide valuable insights into the effect of aging temperature and grain boundary character on carbide precipitation behaviours.

摘要

镍基高温合金和奥氏体不锈钢的晶界处碳化物的析出会显着影响散装材料的晶界相关性能。这项研究使用扫描电子显微镜和透射电子显微镜评估了在晶界工程（GBE）处理的镍基高温合金（Inconel 690）时效过程中碳化物的生长和溶解。在低于1000°C的时效过程中，晶界网络是稳定的。在715和800更低的时效温度℃，没有观察到对Σ3细小碳化物析出物的少数_Ç晶界。相反，板状碳化物邻近Σ3的两侧沉淀_我晶界和在Σ9晶界的一侧，在Σ27和随机晶界上形成大量碳化物沉淀。在900和1000°C的较高时效温度下，较大的碳化物会以Σ9，Σ27和随机晶界的形式沉淀出更一致的形貌。碳化物在这些较高温度下的时效过程中很常见，这促进了其他碳化物的生长和重新分布。这些实验结果为时效温度和晶界特征对碳化物沉淀行为的影响提供了有价值的见解。