Deshielding effects on fatigue crack growth in shape memory alloys- A study on CuZnAl single-crystalline materials
Deshielding effects on fatigue crack growth in shape memory alloys- A study on CuZnAl single-crystalline materials
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DOI：
10.1016/j.actamat.2019.06.042
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发表时间：
2019-09
期刊：
影响因子：
9.4
通讯作者：
Y. Wu;J. Yaacoub;F. Brenne;W. Abuzaid;D. Canadinc;H. Sehitoglu
中科院分区：
文献类型：
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作者：
Y. Wu;J. Yaacoub;F. Brenne;W. Abuzaid;D. Canadinc;H. Sehitoglu
影响形状记忆合金(SMA)疲劳性能的因素，包括疲劳裂纹扩展(FCG)响应，目前还不是很清楚。在这项研究中，我们指出了一种显著降低FCG性能的机制。我们引入了FCG受屏蔽和去屏蔽机制影响的概念，前者增强了材料的电阻，而后者降低了材料的电阻。我们表明，脱壳机制产生了II型和I型(高达5-10 Mpa m1/2)的额外驱动力(正K贡献)，从而加速了裂纹的扩展。正K分量的来源与相对于裂纹尖端高度不对称的局域马氏体变异体形成有关。我们得到的结果ΔK与基于实验位移测量的结果非常一致。总体而言，这项研究通过量化SMA的脱皮机制，促进了我们对SMA FCG的理解。
The factors that affect the fatigue performance of shape memory alloys (SMAs), including fatigue crack growth (FCG) response, is far from being well-understood. In this study, we point to a mechanism that degrades the FCG performance considerably. We introduce the notion of FCG being affected by shielding and deshielding mechanisms, the former enhancing the resistance while the latter reducing the materials’ resistance. We show that the deshielding mechanism creates additional driving forces (positive K contribution) of both Mode II and Mode I types (as much as 5–10 MPa m1/2) which accelerates the crack advance. The origin of the positive K component is associated with the localized martensite variant formation that is highly asymmetric with respect to the crack tip. We derive a resultant ΔK in excellent agreement with that measured based on experimental displacement measurements. Overall, this study represents an advancement of our understanding in FCG of SMAs by quantifying the deshielding mechanism.