Abstract Peak magnetostriction of Fe100-xGax with x around 27 has been attributed to shear modulus softening, analogues to the scenario for a martensitic transformation. Recently, stress-induced local six-layer modulated monoclinic (6 M) martensites have been investigated in Fe-Ga alloy. To identify the spontaneous martensitic transformation behavior, here we performed a comparative study of a Fe74Ga26 alloy with lower D03 ordering degree at the quenched state and with higher D03 ordering degree after subsequent long-term aging. In comparison with the quenched state that bears no martensites, the aged one undergoes spontaneous martensitic transformation upon cooling, and local 6 M martensites are observed after heating from liquid nitrogen temperature to room temperature. It is found that both the ordering degree and the structural stability of D03 phase are significantly improved after long-term aging, which makes the temperature-induced martensites visible. The present finding verifies that martensitic transformation is a universal phenomenon in the magnetostrictive Fe-Ga alloy.

中文翻译：

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有序处理的 Fe 74 Ga 26 合金中的马氏体转变

摘要 Fe100-xGax 的峰值磁致伸缩（x 约为 27）归因于剪切模量软化，类似于马氏体转变的情况。最近，已经在 Fe-Ga 合金中研究了应力诱导的局部六层调制单斜 (6 M) 马氏体。为了确定自发马氏体相变行为，我们在这里对淬火状态下 D03 有序度较低和随后长期时效后 D03 有序度较高的 Fe74Ga26 合金进行了比较研究。与不含马氏体的淬火状态相比，时效状态冷却时发生自发马氏体转变，从液氮温度加热至室温后观察到局部6M马氏体。结果表明，经长期时效后，D03相的有序度和结构稳定性均显着提高，使温度诱发马氏体可见。目前的发现证实了马氏体转变是磁致伸缩 Fe-Ga 合金中的普遍现象。