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| Abstract: |
| A fourth generation single crystal (SC) nickel based cast superalloy DD15 with 1%Ru, 3%Ru, 5%Ru was prepared using vacuum induction single crystal furnace in order to optimize the properties and cost of DD15 alloy. The exposure experiment of three alloys was conducted at 1100 ℃ for 1000 h. The stress rupture properties tests were performed at 1100 ℃ temperature and 137 MPa pressure. The composition optimization of Ru element in DD15 alloy had been studied. It was found that the alloys with different Ru contents all consist of cuboidal γ′ phase embedded coherent in γ phase. The γ′ phase of the alloy all has a size of about 300-500 nm and a volume content of more than sixty percent. The dimension of γ′ precipitates is reduced and uniform with increase of Ru content. Ru element can reduce the distribution ratio of high melting point element, so the microstructural stability is enhanced with Ru content increasing. No topologically close-packed (TCP) phase precipitated in the 5% Ru alloy even after 1000 h exposure. The stress rupture life of the alloy is significantly improved as Ru content rising. The raft breadth decreases slightly as Ru content increases. The specimen with 1% Ru and 3% Ru exhibits the presence of TCP phases and without TCP phases precipitated in fracture specimen with 5% Ru. The density and integrity of γ/γ′ interfacial dislocation network increase as Ru content of the alloy rises. |
| Key words: DD15 alloy Ru element stress rupture life microstructure stability |
| DOI：10.11916/j.issn.1005-9113.22061 |
| Clc Number:TG132.3+2 |
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| Descriptions in Chinese: |
| Ru含量对DD15合金组织稳定性和持久性能的影响 史振学, 刘世忠 (北京航空材料研究院 先进高温结构材料重点实验室, 北京 100095) 摘要： 为优化DD15合金的性能和成本，在真空定向凝固炉中分别制备了含1%Ru、3%Ru和5%Ru的第四代镍基铸造单晶高温合金DD15，三种合金都在1100℃长期时效1000 h，在1100℃/137MPa条件下测试合金的持久性能。研究了DD15中Ru元素的成分优化。结果表明三种不同Ru含量合金都由立方化γ′ 相和γ基体组成，γ′ 相的尺寸约为300~500 nm，其体积分数都超过60%。随着Ru含量增加，γ′ 相的尺寸变小，均匀性增加。Ru元素能减少高熔点元素的分配比，使合金的组织稳定性增加，5%Ru合金长期时效1000h未出现TCP相。合金的持久性能随着Ru含量增加而增加。筏排厚度随Ru含量增加而稍有增加。1%Ru和3%Ru合金断裂后有TCP相析出，而5%Ru合金无TCP相析出。γ/γ′相界面位错网的密度随着Ru含量增加而增加。 关键词：DD15合金；Ru含量；持久性能；组织稳定性 |
