In situ synchrotron diffraction and modeling of non-equilibrium solidification of a MnFeCoNiCu alloy.
In situ synchrotron diffraction and modeling of non-equilibrium solidification of a MnFeCoNiCu alloy.
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DOI：
10.1038/s41598-021-85430-z
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发表时间：
2021-03-15
影响因子：
4.6
通讯作者：
Yu Z
中科院分区：
文献类型：
--
作者：
Schneiderman B;Chuang AC;Kenesei P;Yu Z
利用同步辐射X射线衍射技术，首次研究了激光熔凝Mn 35 Fe 5Co 20 Ni 20 Cu 20合金的凝固机制和偏析行为。在连续凝固的树枝状和枝晶间区域的随机固溶体的瞬态成分演变复杂的同步辐射衍射数据通过任何单一的常规工具，如Rietveld细化的分析。因此，开发了一种结合硬球近似模型、热力学模拟、热膨胀测量和微观结构表征的新方法，以帮助从根本上理解与衍射数据相对应的局部组成、晶格参数和枝晶体积分数的演变。这种方法在不同的方法中产生了自洽的结果。通过这种方法，确定了四个不同的阶段，包括：（I）FCC枝晶凝固，（II）FCC枝晶间区域的凝固，（III）固态相互扩散和（IV）最终冷却与边缘扩散。研究发现，在第一阶段，随着Mn 35 Fe 5Co 20 Ni 20 Cu 20的枝晶凝固，Cu和Mn被排斥到液体中。在第二阶段期间，随着Cu和Mn继续偏析到枝晶间区域，枝晶和枝晶间区域之间的晶格参数差异升级。在完全固化之后，在阶段III期间，晶格参数差异逐渐减小，表明一定程度的组成均匀化。枝晶的体积分数略有增长，从58.3%到65.5%，基于扩散计算中跨枝晶/枝晶间界面的不断变化的组合物分布。事后金相进一步证实，枝晶在最终显微组织中的体积分数为64.7% ± 5.3%。
The solidification mechanism and segregation behavior of laser-melted Mn35Fe5Co20Ni20Cu20 was firstly investigated via in situ synchrotron x-ray diffraction at millisecond temporal resolution. The transient composition evolution of the random solid solution during sequential solidification of dendritic and interdendritic regions complicates the analysis of synchrotron diffraction data via any single conventional tool, such as Rietveld refinement. Therefore, a novel approach combining a hard-sphere approximation model, thermodynamic simulation, thermal expansion measurement and microstructural characterization was developed to assist in a fundamental understanding of the evolution of local composition, lattice parameter, and dendrite volume fraction corresponding to the diffraction data. This methodology yields self-consistent results across different methods. Via this approach, four distinct stages were identified, including: (I) FCC dendrite solidification, (II) solidification of FCC interdendritic region, (III) solid-state interdiffusion and (IV) final cooling with marginal diffusion. It was found out that in Stage I, Cu and Mn were rejected into liquid as Mn35Fe5Co20Ni20Cu20 solidified dendritically. During Stage II, the lattice parameter disparity between dendrite and interdendritic region escalated as Cu and Mn continued segregating into the interdendritic region. After complete solidification, during Stage III, the lattice parameter disparity gradually decreases, demonstrating a degree of composition homogenization. The volume fraction of dendrites slightly grew from 58.3 to 65.5%, based on the evolving composition profile across a dendrite/interdendritic interface in diffusion calculations. Postmortem metallography further confirmed that dendrites have a volume fraction of 64.7% ± 5.3% in the final microstructure.
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过冷CoCrCuFexNi高熵合金的快速凝固与液相分离
影响因子：
4.4
作者：
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DOI：
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发表时间：
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期刊：
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发表时间：
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影响因子：
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作者：
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Yu, Zhenzhen
DOI：
10.1016/j.ijsolstr.2015.04.032
发表时间：
2015-09-01
影响因子：
3.6
作者：
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通讯作者：
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