[7/25] The 4th WPI-AIMR Joint Seminar in FY2014


The 4th WPI-AIMR Joint Seminar in FY2014


First-principles multiscale calculations for microstructure evolution process


Prof. Tetsuo Mohri
(Institute for Materials Research, Tohoku University)


July 25 (Fri.), 2014 16:00-17:00


Seminar Room, 2nd floor, WPI-AIMR Main Bldg.


Multiscale calculations have been attracting broad attentions in materials science community. Among them is the one for microstructure evolution process in alloys by combining atomistic calculations with Phase Field Method (PFM). We start with electronic structure total energy calculations on a set of ordered compounds and extract effective cluster interaction energies through Cluster Expansion Method. Then, for a configurational entropy term, Cluster Variation Method (CVM) in statistical mechanics is employed, which provides us with accurate information of local atomic environment, and configurational freedom is more efficiently described in the free energy than conventional Bragg-Williams approximation. The atomistic free energy derived above is subject to coarse graining operation, which yields Ginzburg-Landau type free energy expression with a generalized gradient energy coefficient which, unlike the case of conventional PFM, turns out to depend on the temperature, local atomic configuration, lattice constant etc. This procedure is applied to calculate time evolution process of Anti-Phase boundary associated with disorder-L10 transition of Fe-base alloys. (This work has been undertaken in collaboration with Profs. M. Ohno at Hokkaido U. and Y. Chen at Tohoku U.)



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