y Creating, probing and confirming tetragonality in bulk FeNi alloys
y Creating, probing and confirming tetragonality in bulk FeNi alloys
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DOI：
10.1016/j.actamat.2020.07.019
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发表时间：
2020-09-01
期刊：
影响因子：
9.4
通讯作者：
Lewis, L. H.
中科院分区：
文献类型：
--
作者：
Maat, N.;McDonald, I.;Lewis, L. H.
本文报道了利用一种独特而简单的加工工具--多驱动器加热炉，在长时间退火过程中同时施加被动、均匀的饱和磁场和张应力所产生的效果。特别是用高能同步X射线衍射仪和磁光克尔显微镜揭示了严重形变和随后退火的等原子FeNi合金的晶体结构和磁畴构型的演变。已知这些合金在天文时间范围内经历了化学有序的四方(L1(0))结构的一阶磁性相变。多驱动退火态样品保持了类似于前驱形变态的四方晶态和织构，与在相同条件下但没有磁场和应力驱动的对照样品相比，具有更小的晶胞体积和更大的c/a比。磁区图像与这些观察结果相呼应：虽然铸态FeNi合金显示出与应力修正立方磁晶各向异性的存在一致的磁区图案，但在多驱动器退火的样品中存在大面积的具有单轴各向异性的磁区。虽然在这些样品中没有显示出化学有序，但提出了一种通过在多驱动炉中使用被动磁梯度来增强扩散来实现有序状态的策略。(C)2020 Acta Materialia Inc.由爱思唯尔有限公司出版。版权所有。
Effects derived from the simultaneous application of passive, uniform saturating magnetic field and tensile stress during long-time annealing utilizing a unique and simple processing tool, the MultiDriver furnace, are reported. In particular, the evolution of the crystalline structure and the magnetic domain configuration of severely deformed and subsequently annealed equiatomic FeNi alloys were revealed by high-energy synchrotron X-Ray diffraction and Magneto-Optic Kerr Microscopy. These alloys are known to undergo a first-order magnetic phase transformation to a chemically ordered tetragonal (L1(0)) structure in astronomical timeframes. MultiDriver-annealed specimens are found to retain a tetragonal crystallographic state and texture that is similar to that of the precursor deformed state, with a smaller unit cell volume and a larger c/a ratio relative to those of control samples that were annealed under the same conditions but without magnetic field and stress drivers. Magnetic domain images echo these observations: while as-cast FeNi alloys exhibit domain patterns consistent with the presence of a stress-modified cubic magnetocrystalline anisotropy, large areas of domains with uniaxial anisotropy are present in MultiDriver-annealed samples. While no chemical order was demonstrated in these samples, a strategy is proposed for achieving the ordered state by employing a passive magnetic gradient in the MultiDriver furnace to enhance diffusion. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.