Atomistic insights into sluggish crystal growth in an undercooled CoNiCrFe multi-principal element alloy

DX Cui and JB Zhang and X Li and Z Liang and X Zhang and Y Yang and HF Wang, JOURNAL OF ALLOYS AND COMPOUNDS, 941, 168881 (2023).

DOI: 10.1016/j.jallcom.2023.168881

Crystal growth in undercooled CoNi, CoNiCr and CoNiCrFe equi-atomic alloys was investigated by mole-cular-dynamics simulation to show atomistic insights into sluggish crystal growth in the undercooled CoNiCrFe multi-principal element alloy (MPEA). The simulation results showed that the growth velocity decreases gradually and the crystallization kinetics became sluggish as the increasing number of principal elements, being qualitatively consistent with the experiments. Independent of the number of principal elements, the activation controlled crystal growth mechanism always played a dominative role. The slug-gish crystal growth phenomenon in the undercooled CoNiCrFe MPEA was found to be due to the increased growth activation energy and the decreased ultimate growth velocity. By converting the atomic displace- ment arose at the process of crystallization into timescales, the contribution of each element to the growth activation energy was quantified for the first time. Consequently, the important role of the Cr element in increasing the growth activation energy was revealed, being qualitatively consistent with experimental findings that the adding amount of Cr element played a dominate role in sluggish crystal growth. An im-plementation of the time dependent Ginzburg-Landau theory for solidification kinetics indicated that the weakened density relaxation capacity of the melt led to a significant decrease of the ultimate growth ve-locity as the increasing number of principal elements. (c) 2023 Elsevier B.V. All rights reserved.

Return to Publications page