AlTiNbMoV、AlTiNbTaZr和AlTiNbMoCr难熔复杂浓缩合金的相组成：预测与实验的关联
Phase Composition of AlTiNbMoV, AlTiNbTaZr and AlTiNbMoCr Refractory Complex Concentrated Alloys: A Correlation of Predictions and Experiment
AI总结：
针对难熔复杂浓缩合金相预测难题，制备三种合金并实验表征其相组成，发现现有半经验参数和TCHEA4数据库下的CALPHAD方法均无法准确预测所有合金相组成，指出了热力学预测工具的现存局限。
摘要：
由于可能的成分空间极为庞大，设计复杂浓缩合金（CCA，也被称为高熵合金HEA）需要可靠且易用的热力学预测工具。多年来，研究人员开发了大量用于相预测的半经验参数。但本文表明，这些参数均无法可靠指示各类难熔CCA的相含量。CALPHAD已被证明是更强大的相预测工具，但其预测仍存在若干局限性。本研究采用混合元素粉末冶金法制备了AlTiNbMoV、AlTiNbTaZr和AlTiNbMoCr三种合金，借助扫描电子显微镜、能量色散X射线光谱和X射线衍射技术研究了它们的相组成与化学成分。除少量污染相（Al₂O₃和Ti(C,N,O)）外，AlTiNbMoV和AlTiNbMoCr合金在1400℃的均匀化温度下呈现单相固溶体显微组织，而AlTiNbTaZr合金中存在基于Al₃Zr₅的金属间化合物。所有简单半经验参数均无法正确预测全部三种合金的相含量。基于TCHEA4数据库的CALPHAD预测仅能以有限的准确度预测相组成，TCHEA4数据库的关键局限在于仅评估了二元和三元相图，无法预测某些更复杂的相。
英文摘要：
Designing complex concentrated alloys (CCA), also known as high entropy alloys (HEA), requires reliable and accessible thermodynamic predictions due to vast space of possible compositions. Numerous semiempirical parameters have been developed for phase predictions over the years. However, in this paper we show that none of these parameters is a robust indicator of phase content in various refractory CCA. CALPHAD proved to be a more powerful tool for phase predictions, however, the predictions face several limitations. AlTiNbMoV, AlTiNbTaZr and AlTiNbMoCr alloys were prepared using blended elemental powder metallurgy. Their phase and chemical composition were investigated by the means of scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Apart from the minor contamination phases (Al2O3 and Ti(C,N,O)), AlTiNbMoV and AlTiNbMoCr exhibited single-phase solid solution microstructure at the homogenization temperature of 1400 °C, while Al3Zr5 based intermetallics were present in the AlTiNbTaZr alloy. None of the simple semiempirical parameter was able to predict phase content correctly in all three alloys. Predictions by CALPHAD (TCHEA4 database) were able to predict the phases with limited accuracy only. Critical limitation of the TCHEA4 database is that only binary and ternary phase diagrams are assessed and some more complex phases cannot be predicted.
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