Crack Type Degradation Behavior of Ni-Base Superalloy Used in Advanced Gas Turbine under Creep Condition.
Crack Type Degradation Behavior of Ni-Base Superalloy Used in Advanced Gas Turbine under Creep Condition.
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先进燃气轮机用镍基高温合金蠕变条件下裂纹型退化行为。
DOI：
10.1299/kikaia.67.280
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Hiroki Abe
中科院分区：
文献类型：
--
作者：
S. Komazaki;T. Shoji;Hideki Chiba;Hiroki Abe
为了阐明定向凝固镍基高温合金CM 247 LC的裂纹型退化机制，利用光学显微镜和扫描电镜研究了蠕变条件下环境和组织变化对裂纹萌生和扩展行为的影响。金相分析表明，表面裂纹的萌生和扩展与内氧化、氮化及晶界碳化物的分解密切相关。表面裂纹萌生于AlN/γ-基体界面，沿沿着γ′和无碳化物晶界扩展。晶界M23 C6碳化物是蠕变空洞萌生的优先位置，蠕变过程中M6 C向M23 C6的转变是内裂纹型退化的关键因素。穿晶开裂主要发生在沿着γ通道上，由于筏状组织的形成，γ通道成为垂直于加载方向的片层。
In order to clarify a crack type degradation mechanism of a directionally solidified Ni-base superalloy CM 247 LC, the effects of environment and microstructural changes on the crack initiation and growth behavior under creep condition have been investigated using an optical and scanning electron microscopes. Metallographic examinations revealed that the surface crack initiation and growth were closely associated with the internal oxidation, nitriding and decomposition of grain boundary carbides. The surface crack initiated at AIN/γ-matrix interface and propagated along a γ′ and carbide-free grain boundary. It was also found that the grain boundary M23C6 carbide was preferential site for creep cavity initiation, and the transformation of M6C to M23C6 during creep was the critical factor of the internal crack type degradation. Furthermore, the transgranular cracking occurred primarily along the γ-channel, which became lamellar constituent perpendicular to the loading direction because of the raft structure formation.