Origin of phase stability in Fe with long-period stacking order as an intermediate phase in cyclic γ−ε martensitic transformation
Origin of phase stability in Fe with long-period stacking order as an intermediate phase in cyclic γ−ε martensitic transformation
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具有长周期堆垛顺序的 Fe 作为循环 γ−ε 马氏体相变中间相的相稳定性起源
DOI：
10.1103/physrevresearch.3.033215
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发表时间：
2021
影响因子：
4.2
通讯作者：
Takahiro Sawaguchi
中科院分区：
文献类型：
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作者：
Takao Tsumuraya;Ikumu Watanabe;Takahiro Sawaguchi
一类Fe-Mn-Si基合金在面心立方(Fcc)相和六方密排(Hcp)相之间表现出可逆的马氏体相变。在形变诱导相变过程中，我们发现了一个与该相不同的相。在该相中，电子衍射点位于与具有2H结构的(Hcp)相平面对应的1/3位置，这意味着长周期堆积有序(LPSO)。为了理解堆积模式和探索LPSO相作为两者之间的中间相的可能性，用密度泛函理论中的自旋极化形式的广义梯度近似的第一性原理计算了不同结构多型铁的相稳定性。我们发现，在候选的LPSO结构中，反铁磁有序结构是最稳定的，并且在能量上最接近该相，这表明所观察到的LPSO相采用了这种结构。此外，我们还确定了相稳定性可以归因于接近费米能级的态密度中的谷深度。
A class of Fe-Mn-Si–based alloys exhibit a reversible martensitic transformation between thephase with a face-centered cubic (fcc) structure and anphase with a hexagonal close-packed (hcp) structure. During the deformation-inducedtransformation, we identified a phase that is different from thephase. In this phase, the electron diffraction spots are located at the 1/3 positions that correspond to theplane of the(hcp) phase with 2H structure, which suggests long-period stacking order (LPSO). To understand the stacking pattern and explore the possible existence of an LPSO phase as an intermediate between theandphases, the phase stability of various structural polytypes of iron was examined using first-principles calculations with a spin-polarized form of the generalized gradient approximation in density functional theory. We found that an antiferromagnetic orderedstructure is the most stable among the candidate LPSO structures and is energetically closest to thephase, which suggests that the observed LPSO-like phase adopts thestructure. Furthermore, we determined that the phase stability can be attributed to the valley depth in the density of states, close to the Fermi level.