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Electrostatic levitation technique and molecular dynamics simulation were performed to investigate the thermophysical properties, liquid structure and crystal growth dependence on undercooling of Ti 85 Ni 10 Al 5 alloy. The liquid Ti 85 Ni 10 Al 5 alloy was substantially undercooled up to 335 K (0.18T L ). As undercooling increased, the potential energy of the liquid alloy decreased and the alloy entered into a high metastable state. At this state, the atoms tended to bond with each other and the clusters were inclined to convert into high-coordinated clusters, as confirmed by the fraction of the high-coordinated clusters variation. The enlarged clusters and enhanced local structure stability contributed to the increase of the thermophysical parameters and crystal growth velocity, and eventually dendrite refinement. The density, the specific heat and the surface tension of liquid alloy exhibited a linear relation with temperature and the shear viscosity of liquid alloy showed exponential variation which showed good agreement with the calculation results by molecular dynamics simulation. The growth velocity first increased slowly and then dramatically once the undercooling exceeded the threshold. The achieved maximum crystal growth velocity was 12.4 m s −1 and it was up to 326 times of the value at 94 K undercooling.

The physical properties of liquid alloy are crucial for many science fields. However, acquiring these properties remains challenging. By means of the deep neural network (DNN), here we presented a deep learning interatomic potential for the Ti–Ni–Cr–Al liquid system. Meanwhile, the thermophysical properties of the Ti–Ni–Cr–Al liquid alloy were experimentally measured by electrostatic levitation and electromagnetic levitation technologies. The DNN potential predicted this liquid system accurately in terms of both atomic structures and thermophysical properties, and the results were in agreement with the ab initio molecular dynamics calculation and the experimental values. A further study on local structure carried out by Voronoi polyhedron analysis showed that the cluster exhibited a tendency to transform into high-coordinated cluster with a decrease in the temperature, indicating the enhancement of local structure stability. This eventually contributed to the linear increase in the density and surface tension, and the exponential variation in the viscosity and the diffusion coefficient with the rise of undercooling.

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