Droplet Free Energy Functional for the Morphology of Martensites

Дата и время публикации : 1996-03-07T10:36:33Z

Авторы публикации и институты :
Madan Rao (Institute of Mathematical Sciences, Madras)
Surajit Sengupta (Indira Gandhi Centre for Atomic Research, Kalpakkam)

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: 5 pages, REVTEX, includes 2 .eps figures To appear in “Defects in Condensed Media”, eds. K. Krishan, C. S. Sundar and V. Kumar (SciTech Publ. Ltd., Switzerland, 1996)
Первичная категория: cond-mat

Все категории : cond-mat

Краткий обзор статьи: Martensites are metastable phases, possessing a characteristic morphology, usually formed during a fast quench accross a structural transition. We attempt to understand these morphological features using a coarsegrained free energy functional ${cal F}[epsilon ; Phi]$ which contains, in addition to the usual strain fields $epsilon_{ij}$ (the “ order parameter” for the transition), the “vacancy” field $phi$ which arises due to the geometric mismatch at a parent-product interface. The relaxation of this mismatch is slow compared to typical front propagation times and hence $phi$ is essentially frozen in the reference frame of the growing martensite front. Minimisation of ${cal F}$ then automatically yeilds typical martensite morphologies. We demonstrate this in two dimensions for the square to rhombus transformation and obtain internally twinned martensites, which grow as thin strips, for “hard” martensites (e.g., Fe-based alloys) or with a `single-interface’, for “soft” martensites (e.g., In-Tl alloys).

Category: Physics