Density, excess volume, and structure of Fe–Cr–Ni melts

Abstract

The relationship between the excess volume and the structure of Fe-Cr-Ni melts is investigated using containerless levitation and in situ high-energy synchrotron x-ray diffraction techniques. The density of six hypoeutectic Fe-Cr-Ni alloys along the 72 wt. % Fe isopleth was measured in the stable and undercooled regions, and the excess volume was evaluated as a function of Cr concentration. It is found that the 72Fe-Cr-Ni alloys exhibit a positive sign of excess volume and the amount increases with increasing Cr concentration. Analysis of the structure factor and pair distribution function of the alloy family reveals that the short-range order in the melt becomes more pronounced with decreasing Cr concentration; this demonstrates a direct correlation between the excess volume and local liquid structure. A characteristic signature of the icosahedral structure is observed in the structure factor of the melts, and the potential origin of the positive excess volume of the 72Fe-Cr-Ni alloys is qualitatively discussed in relation to the icosahedral structure.

Unveiling the mechanism of tuning elemental distribution in high entropy alloys and its effect on thermal stability

“…Experimental observations also indicate that changes in Cr concentration have an impact on the ordering of Cr in the system. Combining in situ synchrotron XRD with containerless levitation techniques, Jeon et al 45 discovered that short range order in the Fe–Cr–Ni melt became more pronounced as the Cr concentration decreased.…”