Creep property and microstructure evolution of a nickel-base single crystal superalloy in 011 orientation
Creep property and microstructure evolution of a nickel-base single crystal superalloy in 011 orientation
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DOI：
10.1016/j.matchar.2013.09.019
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发表时间：
2013-12
影响因子：
4.7
通讯作者：
G. Han;J. J. Yu-J.;Zushu Hu;X. Sun
中科院分区：
文献类型：
--
作者：
G. Han;J. J. Yu-J.;Zushu Hu;X. Sun
研究了一种[011]取向单晶高温合金在700 °C、900 °C和1040 °C温度下的蠕变性能和组织演变。结果表明，在700 °C低温下，蠕变存在第一、稳态和第三阶段。随着温度升高到900 °C和1040 °C的高温，稳态蠕变阶段减少或消失，蠕变曲线的形状由广泛的第三阶段主导。最小蠕变应变速率与所施加的应力呈幂律关系; 700 °C、900 °C和1040 °C下的应力指数分别为28、13和6.5。显微组织观察表明，在700 °C低温和高应力条件下，γ′相的形貌基本保持不变。随着蠕变温度的升高，γ′相倾向于连成一片，形成与应力成45°角的片层组织。透射电子显微镜（TEM）研究表明，< 110 >在700 °C低温下，多个{111}滑移系在基体通道中滑动以及层错或弯曲位错对剪切γ′相是主要的变形机制。在900 °C和1040 °C的高温下，γ/γ′界面形成位错网络，γ′筏被位错对剪切。
The creep property and microstructure evolution of a single crystal superalloy with [011] orientation were investigated at the temperatures of 700 °C, 900 °C and 1040 °C. It is shown that there exist stages of primary, steady-state, and tertiary creep under the lower temperature 700 °C. As the temperature increases to high temperatures of 900 °C and 1040 °C, steady-state creep stage is reduced or disappears and the shape of creep curves is dominated by an extensive tertiary stage. The minimum creep strain rate exhibits power law dependence on the applied stress; the stress exponents at 700 °C, 900 °C and 1040 °C are 28, 13 and 6.5, respectively. Microstructure observation shows that the morphologies of γ′ phase almost keep original shape at the lower temperature 700 °C and high applied stress. With the increasing creep temperature, γ′ precipitates tend to link together and form lamellar structure at an angle of 45° inclined to the applied stress. Transmission electron microscopy (TEM) investigations reveal that multiple < 110 > {111} slip systems gliding in the matrix channels and shearing γ′ precipitates by stacking faults or bending dislocation pairs are the main deformation mechanism at the lower temperature of 700 °C. At the high temperatures of 900 °C and 1040 °C, dislocation networks are formed at γ/γ′ interfaces and the γ′ rafts are sheared by dislocation pairs.