Cube slip and non-Schmid effects in single crystal Ni-base superalloys
Cube slip and non-Schmid effects in single crystal Ni-base superalloys
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DOI：
10.1088/0965-0393/18/1/015005
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发表时间：
2009
影响因子：
1.8
通讯作者：
T. Tinga;W. Brekelmans;Mgd Marc Geers
中科院分区：
文献类型：
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作者：
T. Tinga;W. Brekelmans;Mgd Marc Geers
提出了一种包含镍基高温合金变形行为两个方面的先进本构模型。在这些两相材料中存在多种形变机制。在基体相中，立方体滑移对材料的取向依赖性起着重要作用。此外，析出相的非弹性变形导致了材料响应的非施密德效应。本文通过在基体相的本构关系中加入锯齿形交叉滑移机制来模拟宏观立方体滑移。提出了一种交叉滑移因子，用于量化交叉滑移量，从而表示立方体滑移的方向依赖性。此外，提出了一个详细的沉淀相本构模型，该模型可以模拟非施密德效应，如拉压不对称。交叉滑移机制和相关的γ′相部分位错的分裂是导致异常屈服行为的原因，被纳入模型中。提出的配方在最近开发的单晶镍基高温合金的晶体塑性框架中实现，并确定了商用合金CMSX-4的一致模型参数集。该模型被证明可以合理地预测材料在一定温度和应力或应变率水平下的拉伸响应和蠕变行为。结合基体和沉淀中的交叉滑移机制，充分模拟了材料取向依赖性和实验确定的拉压不对称性。
An advanced constitutive model incorporating two specific aspects of Ni-base superalloy deformation behaviour is proposed. Several deformation mechanisms are active in these two-phase materials. In the matrix phase, cube slip plays an important role in the orientation dependence of the material. Moreover, inelastic deformation of the precipitate phase leads to non-Schmid effects in the material response. Macroscopic cube slip is modelled here by incorporating a zig-zag cross slip mechanism into the constitutive relations for the matrix phase. A cross slip factor is proposed that quantifies the amount of cross slip and consequently represents the orientation dependence of the cube slip. Further, a detailed precipitate phase constitutive model is proposed, which enables the simulation of non-Schmid effects, like the tension–compression asymmetry. The cross slip mechanism and the associated splitting of partial dislocations in the γ′-phase, which are responsible for the anomalous yield behaviour, are incorporated in the model. The proposed formulations are implemented in a recently developed crystal plasticity framework for single crystal Ni-base superalloys and a consistent set of model parameters for the commercial alloy CMSX-4 is determined. The model is shown to reasonably predict the material tensile response and creep behaviour for a range of temperatures and stress or strain rate levels. The incorporation of the cross slip mechanisms in the matrix and precipitate results in an adequate simulation of the material orientation dependence and the experimentally determined tension–compression asymmetry.