Dendrite Growth State Under Non-uniform Temperature Field

In order to grasp the evolution of microstructure under non-uniform temperature field, this work adopted a modified meta-cellular automata model to compare the similarities and differences of microstructure evolution under uniform and non-uniform temperature fields on the basis of completing the algorithm verification, and systematically studied the evolution of dendrite morphology, tip growth rate and solute distribution in the domain as well as the evolution of polycrystalline structure in non-uniform temperature field. The results show that the simulation results of the model is within 1.4% of the error range of the CA-FD mode. The tip rate at the solidification end of the dendrite tends to be stable in the uniform temperature field, while it shows a continuous increase in the non-uniform field. The solid phase solute concentration increases with the extension of the dendrite arm in the non-uniform field, but remains constant in the uniform field. For single dendrite growth in the non-uniform temperature field, the length of dendrite arms reaches 1030 μm when the cooling rate reaches 10 K/s, an increase of 49.3% compared to the uniform field. And the length of dendrite arms reaches 1460 μm when the cooling rate reaches 30 K/s, an increase of 111.6%. The strengthening of the cooling rate increases the solid-phase solute concentration inside the dendrite, and more lateral dendrite arms appear, causing the fluctuation of the solute at the solid/liquid interface, showing an irregular distribution. The average solute concentration in the non-uniform temperature field of the polycrystalline structure increases with the increase of the cooling rate, and the proportion of solid phase in the domain increases from 45% to 65% at the end of solidification with the increase of the cooling rate. While solute enrichment in the domain, multiple dendrite arm generation and dendrite arm coarsening are observed. © 2022 Rare Metals Materials and Engineering Press. All rights reserved.