Composition dependence of tracer diffusion coefficients in Fe–Ga alloys: A case study by a tracer-diffusion couple method
Composition dependence of tracer diffusion coefficients in Fe–Ga alloys: A case study by a tracer-diffusion couple method
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DOI：
10.1016/j.actamat.2020.10.065
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发表时间：
2020-08
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通讯作者：
G. Muralikrishna;B. Tas;N. Esakkiraja;V. Esin;K. C. Kumar;I. Golovin;I. Belova;G. Murch;A. Paul;S. Divinski
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文献类型：
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作者：
G. Muralikrishna;B. Tas;N. Esakkiraja;V. Esin;K. C. Kumar;I. Golovin;I. Belova;G. Murch;A. Paul;S. Divinski
在缺少一种组分的合适的放射性同位素和可靠的热力学参数的情况下，利用一种新的放射性示踪剂-扩散偶技术解决了示踪剂扩散系数的估计问题。这是证明通过产生可靠的和可重复的迁移率数据的合金的Fe-Ga系统具有很强的组成依赖性的扩散系数。在1143 K下，同时测量了Fe/Fe-16 Ga、Fe/Fe-24 Ga和Fe-16 Ga/Fe-24 Ga三对合金中的~（59）Fe示踪和互扩散。对于具有不同端元的耦合，所获得的结果对于重叠的组合物区间彼此非常一致。的摩尔体积上测得的示踪剂-（59 Fe）和互扩散系数的影响进行评估。通过热力学计算，由Darken-Manning关系式确定了Ga在0-24 at.%组分范围内的示踪扩散系数和空位风因子佐治亚州本研究的结果证实了放射性示踪剂扩散偶技术产生高精度扩散数据的可靠性。结果表明，这有助于优化Fe-Ga体系bcc相的迁移率描述。Ga示踪剂扩散系数进一步估计通过实验测定的比率的Fe和Ga示踪剂扩散系数在Kirkendall标记平面和利用Fe示踪剂扩散系数直接测量的放射性示踪剂的方法。
The problem of estimation of the tracer diffusion coefficients is solved by utlizing a novel radiotracer-diffusion couple technique in the absence of a suitable radioisotope of one of the components and reliable thermodynamic parameters. This is demonstrated by generating reliable and reproducible mobility data in the alloys of the Fe–Ga system with a strong composition dependence of the diffusion coefficients. Tracer- (59Fe) and inter-diffusion are simultaneously measured in three couples Fe/Fe-16 Ga, Fe/Fe-24 Ga and Fe-16 Ga/Fe-24 Ga at 1143 K in at.%). The results obtained for the couples with different end-members are in an excellent agreement with each other for the overlapping composition intervals. The influence of the molar volume on the measured tracer- (59Fe) and inter-diffusion coefficients is evaluated. Using thermodynamic calculations, the Ga tracer diffusion coefficient and the vacancy wind factor are determined via the Darken-Manning relation for the composition range of 0–24 at.% Ga. The results in this study confirm the reliability of the radiotracer-diffusion couple technique for producing highly accurate diffusion data. As a result, this helped for optimizing the mobility description of the bcc phase of the Fe–Ga system. The Ga tracer diffusion coefficients are further estimated via experimental determination of the ratio of the Fe and Ga tracer diffusivities at the Kirkendall marker planes and utilizing the Fe tracer diffusion coefficients measured directly by the radiotracer method.