Fig. 1. Schematic of heat source model and grid model. (a) Schematic of heat source model; (b) grid model

Fig. 2. Experimental apparatus

Fig. 3. Temperature field simulation results. (a) Laser keyhole; (b) upper surface of the molten pool; (c) cross-section of the molten pool; (d) longitudinal cross-section of the molten pool

Fig. 4. History of the temperature of the extraction points

Fig. 5. Microstructure evolution process. (a) Planar crystal propulsion; (b) interface instability; (c) competitive growth; (d) stable growth

Fig. 6. Comparisons of primary dendrite arm spacing for simulated and experimental microstructures

Fig. 7. Parameters in different positions. (a) Extracted solidification parameters; (b) the primary dendrite arm spacing and cooling rate

Fig. 8. Comparison of simulated and experimental primary dendrite arm spacings

Fig. 9. Nb element distribution. (a) Distribution of Nb element along the dendrite growth direction; (b) distribution of Nb element perpendicular to the dendrite growth direction

Fig. 10. Comparison of experimental and solute field simulated results

Fig. 11. SEM and EDS analysis. (a) EDS result of Laves phase; (b) SEM image; (c) EDS result of the matrix