Possibility of Spinodal Decomposition in ZrO2-Y2O3 Alloys: A Theoretical Investigation |
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Authors: | Danan Fan Long-Qing Chen |
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Affiliation: | Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 |
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Abstract: | The thermodynamics and kinetics of cubic → tetragonal phase transformations in ZrO2-Y2O3 alloys were investigated by using thermodynamic stability analysis and kinetic computer simulations to explore the possibility of a spinodal mechanism during decomposition. Based on a simple free energy model, it is shown that, depending on the alloy composition, a cubic phase aged within the t + c two-phase field may result in three different sequences of phase transformations: (1) direct nucleation and growth of the equilibrium t-phase from the c-phase matrix; (2) formation of a metastable t'-phase followed by nucleation and growth of the equilibrium c- and t-phases; and (3) formation of a transient t'-phase followed by its spinodal decomposition into two tetragonal phases with one of the tetragonal phases eventually transforming to the equilibrium c-phase. The temporal microstructure evolutions for different compositions were studied by using computer simulations based on the time-dependent Ginzburg-Landau (TDGL) model which incorporates the long-range elastic interactions. |
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