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Microstructure Simulator

The proposed ICMSE approach uses multi-scale computational modeling to guide experiments, and critical experiments to inform and validate the models for fast prototyping ultra-fine and ultra-uniform microstructures for the next generation of Ti alloys. The computational and experimental tasks required to develop this new approach have led to the development of a Microstructure Simulator to predict microstructure evolution as a function of alloy composition and heat treatment, specifically exploiting the new transformation pathways discussed above. The Microstructure Simulator that takes inputs from (a) available thermodynamic and mobility databases and DFT calculations, (b) crystallography (lattice correspondence and orientation relationship) of b®a and b®w transformations from experimental characterization and theoretical predictions and (c) interfacial energies of b/w,  w/a, and  b/a interfaces from DFT calculations, and makes predictions of a+b microstructures (Fig. 1) formed via various conventional and non-conventional transformation pathways upon cooling and heating, incorporating pre-existing metastable phases in the beta phase (such as concentration modulation and w particles) [1], and variant selection by existing dislocations [2, 3], grain boundaries [4], residual stresses and external loads [5].  

 

See https://github.com/shirp83/DMREF-Accelerated-Development-of-Next-Generation-of-Ti-Alloys; https://openkim.org/dev-kim-item/MSMEAM_Gibson_Ti__MO_309653492217_000; https://openkim.org/dev-kim-item/MSMEAM_Dynamo_Gibson_Baskes__MD_080127949983_000 for the available source codes. 

 

 

[1] D. Wang, R. Shi, Y. Zheng, R. Banerjee, H. L. Fraser, Y. Wang, Integrated Computational Materials Engineering (ICME) Approach to Design of Novel Microstructures for Ti-Alloys, JOM, 66 (7) (2014) 1287-1298.

[2] D. Qiu, R. Shi, P. Zhao, D. Zhang, W. Lu, Y. Wang, Effect of low-angle grain boundaries on morphology and variant selection of grain boundary allotriomorphs and Widmanstatten side-plates, Acta Materialia, 112  (2016) 347-360.

[3] D. Qiu, R. Shi, D. Zhang, W. Lu, Y. Wang, Variant selection by dislocations during alpha precipitation in alpha/beta titanium alloys, Acta Materialia, 88  (2015) 218-231.

[4] R. Shi, V. Dixit, G. B. Viswanathan, H. L. Fraser, Y. Wang, Experimental assessment of variant selection rules for grain boundary alpha in titanium alloys, Acta Materialia, 102  (2016) 197-211.

[5] R. Shi, N. Zhou, S. R. Niezgoda, Y. Wang, Microstructure and transformation texture evolution during alpha precipitation in polycrystalline alpha/beta titanium alloys - A simulation study, Acta Materialia, 94  (2015) 224-243.