Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第22卷    第6期    总第159期    2012年6月

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文章编号:1004-0609(2012)06-1624-08
[111]取向镍基单晶合金的组织结构与蠕变行为
苏  勇1, 2,田素贵1,于莉丽1,于慧臣3,张  姝1,钱本江1

(1. 沈阳工业大学 材料科学与工程学院,沈阳 110870;
2. 沈阳化工大学 机械工程学院,沈阳 110142;
3. 北京航空材料研究院,北京 100095
)

摘 要: 通过蠕变曲线的测定及微观组织形貌观察,研究[111]取向镍基单晶合金在高温低应力条件下的组织结构与蠕变行为。结果表明:经完全热处理后,[111]取向单晶合金的组织结构是立方γ′相以共格方式嵌镶在γ基体中,并沿 方向规则排列;在1 040~1 080 ℃、137~180 MPa的温度和应力范围内,该取向单晶合金表现出明显的温度和施加应力敏感性。蠕变期间,γ′相沿与应力轴呈一定角度形成筏状组织,蠕变后期在近断口区域筏状γ′相发生粗化和扭折。[111]取向单晶合金在蠕变期间的变形特征是位错在γ基体通道中运动和剪切筏状γ′相,由于形变量较大,较多位错切入筏状γ′相后使其形成亚晶结构,其中,蠕变后期大量位错切入筏状γ′相导致合金的蠕变抗力降低,是合金发生蠕变断裂的主要原因。

 

关键字: 单晶镍基合金;[111]取向;蠕变;组织演化;亚晶;变形特征

Microstructure and creep behavior of [111] orientation single crystal nickel-based superalloy
SU Yong1, 2, TIAN Su-gui1, YU Li-li1, YU Hui-chen3, ZHANG Shu1, QIAN Ben-jiang1

1. School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China;
2. School of Mechanical Engineering, Shenyang University of Chemical Technology, Shenyang 110142, China;
3. Beijing Institute of Aeronautical Materials, Beijing 100095, China

Abstract:By means of the measurement of creep curves and microstructure observation, the microstructure and creep behavior of a [111] orientation single crystal nickel-base superalloy were investigated under the conditions of high temperatures and low stresses. The results show that, after full heat-treatment, the microstructure of [111] oriented single crystal nickel-base superalloy consists of the cuboidal γ′ phase embedded coherently in the γ matrix, and regularly arranges along the  orientations. In the temperature and stress ranges of 1 040−1 080 ℃ and 137−180 MPa, the superalloy displays an obvious sensibility to the applied temperatures and stresses. During the tensile creep, the cuboidal γ′ phase in the alloy is transformed into the rafted structure at a certain angle relative to the direction of the applied stress. Furthermore, the coarsening and distorting of the rafted γ′ phase occurs in the region near the fracture at the latter stage of creep. The deformation features of the [111] orientation single crystal superalloy during creep are that the slipping of the dislocations is activated in the γ matrix channels and dislocations shear into the rafted γ′ phase. The significant amount of dislocations shear into the rafted γ′ phase, due to the bigger strain occurred to the alloy, to form the subgrain structure during high-temperature creep. In the latter stage of creep, large number of dislocations shear into the rafted γ′ phase for decreasing the creep resistance, which is thought to be the main reason for the creep rupture of the alloy.

 

Key words: single crystal nickel-base superalloy; [111] orientation; creep; structure evolution; subgrain; deformation feature

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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