A comparative investigation in microstructure and mechanical properties of a novel as-cast polycrystalline and single-crystal (SC) Co–9Al–9W–2Ta-0.02B-0.02Ce (at.%) alloy with a growth direction of [0 0 1] has been performed. Aged at 900 °C for 100 h, the polycrystalline and SC alloy consisted of a Co solid solution (γ-Co_SS) matrix and nano-scale cuboidal γ′-Co₃(Al, W) intermetallic precipitates, while the two phases cohered with each other. For the polycrystalline alloy, Ce was observed to segregate primarily at the grain boundaries and the γ′-Co₃(Al, W) phase, and it could exclude impurity O from the grain boundaries. From room temperature (RT) to 900 °C, the SC sample always showed higher yield strength and elongation under tension than the polycrystalline sample except strength at 700 °C, while the flow stress anomalies took place at 700 °C for the polycrystalline alloy, and 800 °C for the SC alloy. Without the grain boundary, the SC alloy had excellent elongation, larger than 15.6% from RT to 900 °C. However, the polycrystalline alloy lost the ductility at temperatures above 600 °C, which was caused by transformation of the failure from a mixed transgranular dimple plus intergranular brittle mode to fully intergranular brittle mode.

生长方向为 [0 0 1 的新型铸态多晶和单晶 (SC) Co-9Al-9W-2Ta-0.02B-0.02Ce (at.%) 合金的微观结构和机械性能的比较研究] 已执行。在 900 °C 下时效 100 h，多晶和 SC 合金由 Co 固溶体 (γ-Co _SS ) 基体和纳米级立方体 γ'-Co ₃ (Al, W) 金属间沉淀物组成，而两相凝聚彼此。对于多晶合金，观察到 Ce 主要在晶界偏析，γ'-Co ₃(Al, W) 相，它可以从晶界中排除杂质 O。从室温 (RT) 到 900 °C，除了 700 °C 的强度外，SC 样品始终表现出比多晶样品更高的屈服强度和拉伸伸长率，而多晶合金的流动应力异常发生在 700 °C， SC合金为800°C。在没有晶界的情况下，SC 合金具有优异的延伸率，从 RT 到 900 °C 大于 15.6%。然而，多晶合金在高于 600 °C 的温度下失去了延展性，这是由混合穿晶凹坑加晶间脆性模式转变为完全晶间脆性模式造成的。