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Competing Interactions between Mesoscale Length-Scales, Order-Disorder, and Martensitic Transformation in Ferromagnetic Shape Memory Alloys
Acta Materialia ( IF 9.4 ) Pub Date : 2020-12-31 , DOI: 10.1016/j.actamat.2020.116616
D. Salas , Y. Wang , T.C. Duong , V. Attari , Y. Ren , Y. Chumlyakov , R. Arróyave , I. Karaman

In the present work, the effects of composition and heat treatments and the resulting microstructural changes on the martensitic transformation and ferromagnetic transition have been investigated in NiCoMnIn metamagnetic shape memory alloys. In this shape memory alloy system, it is observed that upon heat treatments at a wide temperature range, the onset temperature of the martensitic transformation follows a non-monotonic behavior with respect to heat treatment time, and the nature of the non-monotonic behavior is also a function of composition. This behavior cannot be attributed to well-known factors such as precipitation, change in local composition due to the precipitation and/or global degree of order. In this work, a systematic investigation through synthesis, thermal processing and characterization via thermo-physical measurements, transmission electron microscopy and in-situ synchrotron x-ray diffraction experiments has been used to correlate the non-monotonic dependence of the martensitic transformation and ferromagnetic transition temperatures to the evolution of L21 domains arising from a order/disorder phase transition. A thermodynamic model for the magneto-structural transition is combined with classical nucleation theory to further ascertain the role of microstructural length-scales on the onset of the martensitic transformation. This work thus provides understanding of the thermodynamic and kinetic factors that can be controlled to tune the coupled magneto-structural transformations in NiCoMnIn metamagnetic shape memory alloys.



中文翻译:

铁磁形状记忆合金的中尺度长度尺度,有序无序和马氏体转变之间的竞争性相互作用

在目前的工作中,已经研究了NiCoMnIn超磁性形状记忆合金中成分和热处理以及所产生的微观结构变化对马氏体转变和铁磁转变的影响。在该形状记忆合金系统中,观察到在宽温度范围内进行热处理时,马氏体相变的开始温度相对于热处理时间遵循非单调行为,并且非单调行为的性质为也是组成的功能。这种行为不能归因于众所周知的因素,例如降水,由于降水和/或整体有序度引起的局部成分变化。在这项工作中,通过合成,热处理和通过热物理测量进行表征的系统研究,1个域是由有序/无序相变引起的。磁-结构转变的热力学模型与经典成核理论相结合,进一步确定了微观结构长度尺度对马氏体转变开始的作用。因此,这项工作提供了对热力学和动力学因素的理解,可以通过控制这些热力学因素和动力学因素来调节NiCoMnIn亚磁形状记忆合金中耦合的磁结构转变。

更新日期:2021-01-20
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