How atoms of polycrystalline Nb20.6Mo21.7Ta15.6W21.1V21.0 refractory high-entropy alloys rearrange during the melting process

• Published in: Scientific reports Vol. 12; no. 1; p. 5183
• Main Authors: Ju, Shin-Pon, Li, Chen-Chun, Shih, Huai-Ting
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 25-03-2022; Nature Publishing Group; Nature Portfolio
• Subjects: 639/166; 639/301; 639/925; Alloys; Humanities and Social Sciences; Kinetic energy; Melting; Melting point; Molecular dynamics; multidisciplinary; Science; Science (multidisciplinary); Single crystals
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-022-09203-y

The melting mechanism of single crystal and polycrystalline Nb
20.6
Mo
21.7
Ta
15.6
W
21.1
V
21.0
refractory high entropy alloys (RHEAs) were investigated by the molecular dynamics (MD) simulation using the second-nearest neighbor modified embedded-atom method (2NN MEAM) potential. For the single crystal RHEA, the density profile displays an abrupt drop from 11.25 to 11.00 g/cm
3
at temperatures from 2910 to 2940 K, indicating all atoms begin significant local structural rearrangement. For polycrystalline RHEAs, a two-stage melting process is found. In the first melting stage, the melting of the grain boundary (GB) regions firstly occurs at the pre-melting temperature, which is relatively lower than the corresponding system-melting point. At the pre-melting temperature, most GB atoms have enough kinetic energies to leave their equilibrium positions, and then gradually induce the rearrangement of grain atoms close to GB. In the second melting stage at the melting point, most grain atoms have enough kinetic energies to rearrange, resulting in the chemical short-ranged order changes of all pairs.