Record Details

Microstructure Evolution In Semisolid Processing

Electronic Theses of Indian Institute of Science

View Archive Info
 
 
Field Value
 
Title Microstructure Evolution In Semisolid Processing
 
Creator Apoorva, *
 
Subject Aluminium Alloys - Microstructures
Microstructural Evolution
Reheating - Enthalpy Method
Eutectic Solidification
Globularization
Multiphase Solidification
Microstructure Modelling
Semisolid Processing
Heat Treatment - Phase Field Method
Gibbs Thomson Effect
Phase Field
Metallurgy
 
Description In this thesis, we present an experimental and numerical study of globularization during reheating of thixocast billet having non-dendritic microstructure. The process of reheating is an important step in the semisolid processing and is essential to control its microstructure and hence its mechanical properties. Material chosen for this study is Aluminum alloy, A356. The primary focus of this study is the heat treatment below eutectic temperature i.e. transformation in solid phase. It is found that during short duration heat treatment, globularization of primary α grains and spheroidization of eutectic Si flakes take place which improves the mechanical properties of semisolid cast products significantly. A prolonged heat treatment is found to degrade the properties of castings since it enhances the porosity and coarsening of Si. The study suggests that a precise heat treatment practice can be designed to improve the semisolid microstructure. A computational model based on Phase field approach has been proposed to study this phenomena. Predictions based on this model are qualitatively compared with corresponding experimental observations. Since eutectics form an important step in multiphase solidification, an attempt has been made to develop an enthalpy based explicit micro-scale model for eutectic solidification. In this preliminary study, growth of adjacent α and β phases in a two dimensional Eulerian framework has been simulated. The model is qualitatively validated with Jackson Hunt theory. Results show expected eutectic growth. This methodology promises significant saving in computational time compared to existing numerical models.
 
Contributor Dutta, Pradip
 
Date 2014-09-09T07:46:03Z
2014-09-09T07:46:03Z
2014-09-09
2011-08
 
Type Thesis
 
Identifier http://etd.iisc.ernet.in/handle/2005/2382
http://etd.ncsi.iisc.ernet.in/abstracts/3065/G25284-Abs.pdf
 
Language en_US
 
Relation G25284