Detection and quantification of D03 chemical order in Fe-Ga alloys using high resolution X-ray diffraction
Detection and quantification of D03 chemical order in Fe-Ga alloys using high resolution X-ray diffraction
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DOI：
10.1016/j.msea.2005.10.035
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发表时间：
2006-01-25
期刊：
影响因子：
6.4
通讯作者：
Summers, EM
中科院分区：
文献类型：
--
作者：
Lograsso, TA;Summers, EM
Fe-Ga合金的磁致伸缩随Ga含量的增加而显著增加，在Ga在BCC α - fe （A2）中的溶解度极限附近达到最大值。在这个极限下，磁致伸缩取决于样品的热历史和长程化学有序D0(3)相的形成。然而，由于A2和D0(3)相的单位胞几乎相同，Fe和Ga的原子散射因子相似，因此Fe-Ga合金中相混合的检测和定量存在问题。这项工作证明了使用高分辨率粉末x射线衍射来检测Fe-Ga合金中两相混合物的存在。无论是否可以检测到有序结构的超晶格反射，都可以分辨出主反射的峰分裂。从K α (1)-K α(2)在中高2 θ值的分裂中可以清楚地看出这种峰分裂，并且样品的纹理不会干扰或掩盖峰分裂。定量分析显示Fe-19.5 at。% Ga在高温淬火时为100% A2，但在缓慢冷却时为两相混合物，67% A2和33% D0(3)体积。相反，Fe-22 at。% Ga合金为两相混合物，淬火时为40% A2和60% D0(3)，慢冷时为100% D0(3)。(c) 2005 Elsevier B.V.版权所有
Fe-Ga alloys have exhibited significant increases in magnetostriction as a function of Ga content, reaching a maximum near the solubility limit of Ga in BCC alpha-Fe (A2). At this limit, the magnetostriction is dependent on the thermal history of the sample and the formation of long-range chemically ordered D0(3) phase. However, due to nearly identical unit cells of A2 and D0(3) phases and similar atomic scattering factors of Fe and Ga, detection and quantification of phase mixtures in Fe-Ga alloys is problematic. This work demonstrates the use of high resolution powder X-ray diffraction in detecting the presence of two-phase mixtures in Fe-Ga alloys. Peak splitting of the primary reflections is resolved, irrespective of whether or not superlattice reflections from the ordered structure are detectable. This peak splitting is clearly discernible from K alpha(1)-K alpha(2) splitting at moderate and high 2 theta values and texturing of the samples does not interfere or mask the peak splitting. Quantitative analysis showed Fe-19.5 at.% Ga was 100% A2 when quenched from high temperatures, but was a two-phase mixture, 67% A2 and 33% D0(3) by volume, when slow cooled. Conversely, Fe-22 at.% Ga alloy was a two-phase mix, 40% A2 and 60% D0(3) when quenched and 100% D0(3) when slow cooled. (c) 2005 Elsevier B.V. All rights reserved.