Predicting the columnar-to-equiaxed transition for a distribution of nucleation undercoolings

Autor(es)

Martorano, M. A. ^[1] ; Biscuola, V. B. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Met & Mat Engn, BR-05508900 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: ACTA MATERIALIA; v. 57, n. 2, p. 607-615, JAN 2009.
• Citações Web of Science: 35

Resumo

A deterministic mathematical model for steady-state unidirectional solidification is proposed to predict the columnar-to-equiaxed transition. In the model, which is an extension to the classic model proposed by Hunt {[}Hunt JD. Mater Sci Eng 1984;65:75], equiaxed grains nucleate according to either a normal or a log-normal distribution of nucleation undercoolings. Growth maps are constructed, indicating either columnar or equiaxed solidification as a function of the velocity of isotherms and temperature gradient. The fields A columnar and equiaxed growth change significantly with the spread of the nucleation undercooling distribution. Increasing the spread Favors columnar solidification if the dimensionless velocity of the isotherms is larger than 1. For a velocity less than 1, however, equiaxed solidification is initially favored, but columnar solidification is enhanced for a larger increase in the spread. This behavior was confirmed by a stochastic model, which showed that an increase in the distribution spread Could change the grain structure from completely columnar to 50% columnar grains. (c) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 03/08576-7 - Modelagem matemática da solidificação de ligas binárias sob efeito de convecção natural no líquido e movimentação da fase sólida
• Beneficiário: Marcelo de Aquino Martorano
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores