*3.2. Calculation of the Solute Field*

Figure 4 shows the morphology of dendrite growth under different solute field treatment methods. Figure 4a is the solute distribution method and Figure 4b is the solute extrapolation method.

In the first method, the lower end of the dendrite grew faster, because the dendrite covered the original high-concentration solute domain during the settlement of the dendrite. Through the uniform distribution of solutes, the solute gradient at the upstream end of the dendrite is reduced, so it has a faster growth rate. In contrast, dendrite growth using the solute extrapolation method was more uniform. This article compares the two methods to calculate the average regional concentration at the time of solidification time of 0.3 s, 0.5 s, 0.7 s. It is found that the solute field of Method 1 changes greatly, and the average solute concentrations at the corresponding moments are 4.682%, 4.673%, 4.658% (standard is 4.7%), solute field conservation is always 4.7% in Method 2. It can be seen that the solute field treatment in the second method is more accurate.

**Figure 4.** Dendritic morphology evolution diagram under different methods. (**a**) Method 1; (**b**) Method 2.
