The microstructure formed during solidification has a significant impact on the mechanical properties of materials.In this study,a two-dimensional(2D)cellular automaton(CA)-finite difference(FD)-CALPHAD model was deve...The microstructure formed during solidification has a significant impact on the mechanical properties of materials.In this study,a two-dimensional(2D)cellular automaton(CA)-finite difference(FD)-CALPHAD model was developed to simulate the formation of microstructure and solute segregation in the solidification processes of ternary alloys.In the model,dendritic growth is simulated using the CA technique,while solute diffusion is solved by the FD method,and the CALPHAD method is employed to calculate thermodynamic phase equilibrium during solidification.The CA-FD-CALPHAD coupled model is capable of reproducing the evolution of continuous nucleation and growth of grains as well as the evolution of the microstructure and solute distribution during solidification of ternary alloys.In this study,Al–Zn–Mg ternary alloy is taken as an example to simulate the growth of equiaxed and columnar grains and the columnar-to-equiaxed transition(CET)under different solidification conditions.The simulation results are compared with experimental data from the literature,showing a good agreement.Besides,the study also investigates the evolution of temperature and multicomponent solute fields during solidification and the effects of alloy composition and cooling rate on the microstructure morphology.The results reveal that the initial alloy composition and cooling rate significantly affect dendritic morphology and solute segregation.Higher initial alloy concentrations promote the growth of side branches in equiaxed grains,leading to more pronounced solute segregation between dendrites.As the cooling rate increases,the average grain size of the equiaxed grains decreases accordingly.Additionally,a higher cooling rate accelerates the columnar-to-equiaxed transition,leading to a finer grain structure.展开更多
This work studies the impact of the carbon diffusion on the growth kinetics of austenite and the solute segregation,by utilizing the phase-field(PF)method to simulate the solidification of a Fe-C binary alloy.It is re...This work studies the impact of the carbon diffusion on the growth kinetics of austenite and the solute segregation,by utilizing the phase-field(PF)method to simulate the solidification of a Fe-C binary alloy.It is revealed that increasing the ratio of the carbon diffusion coefficient in solid to that in liquid is advantageous in reducing the solute segregation,and a novel microsegregation model is developed based on the quantitative analysis of the results from PF simulations.The simplified one-dimensional diffusion simulation is employed to analyse the quantitative relationship between the parameters of the proposed microsegregation model and the properties of materials.The universality and reliability of the new microsegregation model are then validated by comparing with the experimental data of various alloy systems.These findings contribute to our comprehension of the fundamental theory of solidification and also provide a potential and promising approach to controlling the solidification microstructure.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52301035)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20230844)the National Key Research and Development Program of China(Grant No.2023YFB3710202).
文摘The microstructure formed during solidification has a significant impact on the mechanical properties of materials.In this study,a two-dimensional(2D)cellular automaton(CA)-finite difference(FD)-CALPHAD model was developed to simulate the formation of microstructure and solute segregation in the solidification processes of ternary alloys.In the model,dendritic growth is simulated using the CA technique,while solute diffusion is solved by the FD method,and the CALPHAD method is employed to calculate thermodynamic phase equilibrium during solidification.The CA-FD-CALPHAD coupled model is capable of reproducing the evolution of continuous nucleation and growth of grains as well as the evolution of the microstructure and solute distribution during solidification of ternary alloys.In this study,Al–Zn–Mg ternary alloy is taken as an example to simulate the growth of equiaxed and columnar grains and the columnar-to-equiaxed transition(CET)under different solidification conditions.The simulation results are compared with experimental data from the literature,showing a good agreement.Besides,the study also investigates the evolution of temperature and multicomponent solute fields during solidification and the effects of alloy composition and cooling rate on the microstructure morphology.The results reveal that the initial alloy composition and cooling rate significantly affect dendritic morphology and solute segregation.Higher initial alloy concentrations promote the growth of side branches in equiaxed grains,leading to more pronounced solute segregation between dendrites.As the cooling rate increases,the average grain size of the equiaxed grains decreases accordingly.Additionally,a higher cooling rate accelerates the columnar-to-equiaxed transition,leading to a finer grain structure.
基金supported by the National Science and Technology Major Project(Grant No.J2019-VI-0019-0134)the National Natural Science Foundation of China(Grant No.52203301)+1 种基金the China Postdoctoral Science Foundation(Grant No.2021TQ0335)the Liaoning Province Science and Technology Plan Joint Fund(Doctoral Research Initiation Project)(Grant No.2024-BSLH-195).
文摘This work studies the impact of the carbon diffusion on the growth kinetics of austenite and the solute segregation,by utilizing the phase-field(PF)method to simulate the solidification of a Fe-C binary alloy.It is revealed that increasing the ratio of the carbon diffusion coefficient in solid to that in liquid is advantageous in reducing the solute segregation,and a novel microsegregation model is developed based on the quantitative analysis of the results from PF simulations.The simplified one-dimensional diffusion simulation is employed to analyse the quantitative relationship between the parameters of the proposed microsegregation model and the properties of materials.The universality and reliability of the new microsegregation model are then validated by comparing with the experimental data of various alloy systems.These findings contribute to our comprehension of the fundamental theory of solidification and also provide a potential and promising approach to controlling the solidification microstructure.
