Size effects of γ′ precipitate on the creep properties of directionally solidified nickel-base super-alloys at middle temperature
Size effects of γ′ precipitate on the creep properties of directionally solidified nickel-base super-alloys at middle temperature
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DOI：
10.1016/j.commatsci.2009.03.023
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发表时间：
2009-08-01
影响因子：
3.3
通讯作者：
Zhuang, Z.
中科院分区：
文献类型：
--
作者：
Nie, J. F.;Liu, Z. L.;Zhuang, Z.
镍基高温合金由镍基体的γ相和析出物的γ'相两相组成，它们均匀地分散在基体中。 γ'沉淀物的形态和尺寸对合金的蠕变性能有很大影响。在中温（850℃）下，析出相的漂流效应不明显，析出相的尺寸效应占主导地位。本文建立了晶体塑性本构模型，考虑损伤和应变梯度来反映蠕变性能的尺寸效应。该模型作为用户材料 (UMAT) 接口在 ABAQUS 中实现。使用具有相同体积分数的合金晶胞模型研究了两种不同的沉淀物尺寸。通过与实验数据的比较，模拟结果合理地证明了析出物对镍基高温合金蠕变性能的显着尺寸效应，这表明当析出物尺寸较小且分数恒定时，蠕变速率较低，断裂寿命较长。 (C) 2009 Elsevier B.V. 保留所有权利。
Nickel-base super-alloys consist of two phases named gamma-phase of nickel matrix and gamma'-phase of precipitates, which are dispersed uniformly in the matrix. The morphologies and sizes of gamma' precipitates have strong effects on the creep properties of the alloys. At the middle temperature (850 degrees C), the rafting effect of the precipitate is not obvious, and the size effects of precipitates are dominant In this paper, a crystal plasticity constitutive model is developed, which considers damage and strain gradient to reflect the size effect of the creep property. This model is implemented into ABAQUS as an interface of user material (UMAT). Two different precipitate sizes are studied using a unit-cell model of alloys with the same volume fraction. By Comparison with the experiment data, the simulation results are reasonable to demonstrate the significant size effect of precipitates on the creep properties of nickel-base super-alloys, which indicates that the creep rates are lower and the rupture lives are longer when the precipitate sizes are smaller with constant fraction. (C) 2009 Elsevier B.V. All rights reserved.