Cyclic degradation mechanisms in aged FeNiCoAlTa shape memory single crystals
Cyclic degradation mechanisms in aged FeNiCoAlTa shape memory single crystals
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DOI：
10.1016/j.actamat.2014.06.019
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发表时间：
2014-10
期刊：
影响因子：
9.4
通讯作者：
P. Krooss;C. Somsen;T. Niendorf;M. Schaper;I. Karaman;Y. Chumlyakov;G. Eggeler;H. Maier
中科院分区：
文献类型：
--
作者：
P. Krooss;C. Somsen;T. Niendorf;M. Schaper;I. Karaman;Y. Chumlyakov;G. Eggeler;H. Maier
本研究重点研究[0 0 1]取向Fe41Ni28Co17Al11.5Ta2.5(at.%)单晶的功能稳定性。结果表明，老化的 FeNiCoAlTa（含有直径约为 5-8 nm 的细分散 γ' 颗粒）的功能退化是由不同马氏体变体在拉伸循环载荷下的相互作用引起的。高达 4.5% 总应变的超弹性循环实验导致永久应变的积累，这主要是由于残余马氏体的形成造成的。进行原位观察是为了评估细观和微观尺度上的局部应变演化和马氏体变体相互作用。光学显微镜和透射电子显微镜观察揭示了各种不同取向的马氏体变体，这些变体在 100 个超弹性循环后仍保留。此外，机械循环后，在γ'析出物附近发现了残留的细小马氏体结构，这对于铁基形状记忆合金的循环降解很重要。
This study focuses on the functional stability of [0 0 1]-oriented Fe41Ni28Co17Al11.5Ta2.5(at.%) single crystals. It is shown that functional degradation of aged FeNiCoAlTa, containing fine dispersed γ′-particles ∼5–8 nm in diameter is caused by the interaction of different martensite variants under cyclic loading in tension. Superelastic cycling experiments up to 4.5% total strain resulted in the accumulation of permanent strain mainly caused by the formation of retained martensite. In situ observations were conducted in order to evaluate the local strain evolution and martensite variant interactions on the meso- and microscale. Optical microscopy and transmission electron microscopy observations revealed various differently oriented martensite variants which were retained upon 100 superelastic cycles. In addition, fine martensitic structures remaining in the vicinity of the γ′ precipitates were found after mechanical cycling, which are shown to be important for cyclic degradation in Fe-based shape memory alloys.