Experimental study and cellular automaton simulation on solidification microstructure of Mg-Gd-Y-Zr alloy

The solidification microstructure of Mg-Gd-YZr alloy was investigated via an experimental study and cellular automaton (CA) simulation. In this study, stepshaped castings were produced, and the temperature variation inside the casting was recorded using thermocouples during the solidification process. The effects of the cooling rate and Zr content on the grain size of the Mg-Gd- Y-Zr alloy were studied. The results showed that the grain size decreased with an increase in the cooling rate and Zr content. Based on the experimental data, a quantitative model for calculating the heterogeneous nucleation rate was developed, and the model parameters were determined. The evolution of the solidification microstructure was simulated using the CA method, where the quantitative nucleation model was used and a solute partition coefficient was introduced to deal with the solute trapping in front of the solid-liquid (S/L) interface. The simulation results of the grain size were in good agreement with the experimental data. The simulation also showed that the fraction of the eutectics decreased with an increasing cooling rate in the range of 2.6-11.0 degrees C.s(-1), which was verified indirectly by the experimental data.

Automated summary

The solidification microstructure of Mg-Gd-YZr alloy was studied through experiments and CA simulation. It was found that grain size decreased with increasing cooling rate and Zr content. A quantitative model for calculating heterogeneous nucleation rate was developed based on experimental data, and CA simulation results matched well with experimental data, showing a decrease in eutectic fraction with increasing cooling rate.