Static coarsening of titanium alloys in single field by cellular automaton model considering solute drag and anisotropic mobility of grain boundaries |
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Authors: | Chuan Wu He Yang HongWei Li XiaoGuang Fan |
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Institution: | State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an710072, China |
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Abstract: | Static coarsening is an important physical phenomenon that influences microstructural evolution and mechanical properties.
How to simulate this process effectively has become an important topic which needs to be dealt with. In this paper, a new
cellular automaton (CA) model, which considers the effect of solute drag and anisotropic mobility of grain boundaries, was
developed to simulate static grain coarsening of titanium alloys in the beta-phase field. To describe the effect of the drag
caused by different solute atoms on coarsening, their diffusion velocities in beta titanium were estimated relative to that
of titanium atoms (Ti). A formula was proposed to quantitatively describe the relationship of the diffusion velocity of Ti
to that of solute atoms; factors influencing the diffusion velocity such as solute atom radius, mass, and lattice type were
considered. The anisotropic mobility of grain boundaries was represented by the parameter c
0, which was set to 1 for a fully anisotropic effect. These equations were then implemented into the CA scheme to model the
static coarsening of titanium alloys Ti-6Al-4V, Ti17 (Ti-5Al-4Mo-4Cr-2Sn-2Zr, wt%), TG6 (Ti-5.8Al-4.0Sn-4.0Zr-0.7Nb-1.5Ta-0.4Si-0.06C,
wt%) and TA15 (Ti-6Al-2Zr-1Mo-1V, wt%) in the beta field. The predicted results, including coarsening kinetics and microstructural
evolution, were in good agreement with experimental results. Finally, the effects of time, temperature, and chemical composition
on grain coarsening and the limitations of the model were discussed. |
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Keywords: | static grain coarsening cellular automaton model solute drag anisotropic mobility titanium alloys |
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