The increasing pursuit of advanced aero-engines with lower ratio between the cost and performance has greatly promoted the demanding of single crystal superalloys characterized by low cost and outstanding temperature capability. In this study, a novel low-cost single crystal superalloy was designed and the creep tests as well as micro-characterization were carried out on the experimental alloy. The results illustrated that the novel single crystal alloy exhibited an ideal microstructural stability without precipitating TCP phases, after long-term thermal exposure at the ultimate service temperature of third generation single crystal superalloys. Moreover, the experimental alloy with only 3 wt% Re addition demonstrated remarkable creep resistance and maintained a very low minimum creep rate at 1100 °C/137 MPa and 1120 °C/137 MPa, while the accumulation and coalescence of micro-pores had eventually led to the alloy fracture. Apart from that, the compact interfacial dislocation networks the 2nd γ′ phase were observed after high-temperature creep rupture, and the typical a < 010 > superdislocations with relatively poor mobility was found at 1120 °C. At 760 °C/800 MPa, both the minimum creep velocity and entire creep stain was increased evidently, however, the ultimate creep rupture life of the alloy had still reached 200 h. The corresponding deformation mechanism was identified as the combination of superdislocation pairs shearing and a/3 < 121 > partial dislocation cutting the γ′ phase with a SISF being generated. In general, the novel single crystal alloy characterized by remarkable mechanical properties and cost reduction possesses a great potential for future application in the advanced aircraft engines.

Graphic abstract

At high temperature and low stress creep condition, the compact interfacial dislocation networks the 2nd γ^′ phases were observed, and the rafted γ^′ phase were ultimately sheared by both a<101> and a<010> superdislocation pairs. At medium temperature and high stress condition, the combined deformation mechanisms of superdislocation pairs shearing and a/3 <121> partial dislocation cutting the γ^′ phase with a SISF being generated were identified.

中文翻译：

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一种新型低成本单晶高温合金的显微组织稳定性和蠕变性能

对低成本性能比的先进航空发动机的日益追求极大地促进了对具有低成本和优异温度性能的单晶高温合金的需求。在这项研究中，设计了一种新型低成本单晶高温合金，并对实验合金进行了蠕变试验和微观表征。结果表明，在第三代单晶高温合金的极限使用温度下长期热暴露后，新型单晶合金表现出理想的微观结构稳定性，而不会沉淀出 TCP 相。此外，仅添加 3 wt% Re 的实验合金表现出显着的抗蠕变性，并在 1100 °C/137 MPa 和 1120 °C/137 MPa 下保持非常低的最小蠕变速率，而微孔的积累和聚结最终导致合金断裂。除此之外，在高温蠕变破裂后观察到第二γ'相的致密界面位错网络，并且在1120°C发现具有相对较差迁移率的典型a<010>超位错。在 760 ℃/800 MPa 时，最小蠕变速度和整体蠕变应变均明显增加，但合金的极限蠕变断裂寿命仍达到 200 h。相应的变形机制被确定为超位错对剪切和 a/3 < 121 > 部分位错切割 γ' 相的组合，并产生 SISF。一般来说，

图形摘要

在高温低应力蠕变条件下，观察到紧密的界面位错网络，即第二 γ ^'相，筏状 γ ^'相最终被 a<101> 和 a<010> 超位错对剪切。在中温高应力条件下，确定了超位错对剪切和a/3 <121> 部分位错切割γ ^'相并产生SISF的组合变形机制。