Pt丝型芯撑对DD5单晶高温合金组织和性能的影响

Effect of core support made of Pt on the microstructure and property of DD5 single crystal superalloy

摘要:

为保证内腔尺寸精度,复杂空心单晶涡轮叶片通常采用Pt丝型芯撑固定陶瓷型芯,然而Pt丝型芯撑对单晶涡轮叶片基体组织和性能的影响规律研究未见报道。本文以DD5二代单晶高温合金为研究对象,通过在单晶薄板中插入Pt丝型芯撑模拟研究型芯撑对于涡轮叶片基体组织和成分偏析的影响,同时测试插入Pt丝型芯撑后DD5合金薄板的典型性能,明确型芯撑对于合金性能的影响规律。结果表明：Pt丝型芯撑与DD5合金基体熔接效果好,无明显异质界面,Pt丝完全合金化,其组织与DD5合金基体组织一致,未形成新相。Pt丝型芯撑的插入对于DD5合金基体组织的影响不大,但导致合金元素偏析程度升高。此外,Pt丝型芯撑的插入对DD5合金薄板的室温拉伸、870℃拉伸及1093℃/158MPa持久性能未产生明显负面影响,合金的断裂模式为枝晶间开裂,裂纹沿碎裂的碳化物及碳化物与基体界面处萌生并扩展。

关键词:Pt;型芯撑;DD5合金;显微组织;力学性能

Abstract:

In order to ensure the accuracy of internal dimension, core supports made of Pt are normally used in the complex hollow single crystal turbine blades. However, the influence of core supports on the microstructure and property of DD5 single crystal turbine blades has not been reported. In this paper, core supports made of Pt were inserted into DD5 thin-wall plate specimens to observe the effect of core support on the microstructure and element segregation. In addition, the typical properties of DD5 thin-wall plate specimens with core support made of Pt were tested to clarify the influence of core support on alloy properties. The results showed that core support made of Pt had great bonding with DD5 alloy without obvious heterogeneous interface. The core support made of Pt was completely alloyed, the microstructure of core support was consistent with DD5 alloy, no new phase was observed. Core support made of Pt had no influence on the microstructure of DD5 alloy, but the degree of element segregation of DD5 alloy was increased. Moreover, core support made of Pt had no negative effect on the tensile property at room temperature, tensile property at 870℃ as well as stress rupture property at 1093℃/158MPa of DD5 thin-wall plate specimens. The fracture mode of DD5 thin-wall plate specimens with core support was interdendritic rupture, and cracks initiated and propagated along the interface between carbide and matrix.

Key words:Pt, core;support, DD5, microstructure, mechanical;property