Abstract:The mechanical properties of metals are closely related to the microstructure. As the most common solidified microstructure, dendrite has a great influence on the microstructure, and the change of temperature has a significant influence on the microstructure. Domestic and foreign scholar have carried out a lot of studies on the relationship between dendrite growth state and the properties of alloys, however, the study of microstructure growth in uniform temperature field usually ignores the effect of temperature on dendrite growth, which has certain limitations. Therefore, an improved cellular automata model was used to study the effect of temperature variation on dendrite growth in a non-uniform temperature field. The dendrite morphology, dendrite tip growth rate and solute distribution in melt were compared and analyzed under non-uniform temperature field and uniform temperature field. The results show that the dendrite morphology and solute distribution in melt are significantly changed with the change of temperature during the growth process of single dendrite. When the initial undercooling degree is 10K in the undercooled melt, the dendritic arm length of the solidification terminal reaches 1030μm at a cooling rate of 10K/s, which is increased by 49.3% compared with the dendritic arm length of uniform temperature field under the same conditions. When the cooling rate reaches 30K/s, the length of dendrite arm reaches 1460μm, which increases by 111.6%. As the cooling rate increases, the concentration of solid solute in the dendrite increases, but the solute fluctuated at the solid-liquid interface, which results in the non-conservation of solute concentration at the solid-liquid interface and irregular distribution, and more lateral dendrite arms appear. For the growth of multi-dendrite, the solid fraction of the alloy reaches 45% at the cooling rate of 10K/s, which is 15.9% higher than that at isothermal condition. When the cooling rate is up to 30K/s, the solidification area of the alloy accounts for 65%, an increase of 35.9% compared with that in the isothermal state. At the same time, several dendrite arms and the coarsening of dendrite arms are observed in the model domain.