msepostdoc-list Seminar for Suryanarayana V. Karra Tuesday. Dec. 1, 3:30 p.m. FRNY B124 "Phase Field Methods on Grain Growth Studies and Grain boundary Phase Transitions" PhD Preliminary Exam

[Coar, Stacey L]

Please consider attending the PhD Preliminary Exam Seminar for Suryanarayana V. Karra held on Tuesday, December 1, 2015, in FRNY B124 at 3:30  p.m.  "Phase field Methods on Grain Growth Studies and Grain Boundary Phase Transitions"



MATERIALS SCIENCE AND ENGINEERING
SEMINAR


"Phase Field Methods on Grain Growth Studies and Grain Boundary Phase Transitions"

By

Suryanarayana Vikrant Karra
Purdue MSE Preliminary Exam
Advisor:
Professor R. Edwin Garcia

ABSTRACT

The shape, size and size distribution of grains affect the physical and mechanical properties of a wide range of materials for industrial applications.  The experimental and computational studies of grain growth for shape and size distribution of grains are necessary steppingstones to first understand and then engineer the macroscopic properties. In this context, the aim of this report is to review the most representative contributions of the scientific literature on phase field models pertaining to grain growth in dense and porous polycrystalline structures.  The types of models presented in this report include: (1) Landau Polynomial model, which is a multiorder parameter description based on a polynomial uniform free energy to study the grain coarsening of porous polycrystalline materials; (2) Multiphase field model, which is also a multiorder parameter model constructed on a pairwise interaction of order parameters to describe the grain growth of fully dense polycrystalline material; and (3) KWC (Kobayashi, Warren, Carter) model, which is an extension of a solidification model described by two order parameters: a crystallinity and local orientation order parameters. Landau Polynomial and Multiphase field methods fall short because of: (1) The extent of the model is constrained by number of grains of the system, (2) The grain boundary character is independent of the degree of misorientation. Similarly, the KWC model is only applicable to describe grain growth of fully dense polycrystalline materials. To study grain growth of porous polycrystalline materials, a model is proposed that brings together the best qualities of both the multiphase field and KWC models, including a degree of crystallinity, local orientation and concentration of vacancies. The structural stability of grain boundaries is described by extending a graphical construction proposed by Tang, and isomorphic to the one pioneered by Cahn, which shows that vacancies stabilize the grain boundaries from premelting.

Date:         Tuesday, December 1, 2015

Time:      3:30 P.M.
Place:    FRNY B124

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