The columnar to equiaxed transition of horizontal unsteady-state directionally solidified Al-Si alloys

• Autor(a) principal: CARVALHO, Diego de Leon Brito
• Data de Publicação: 2014
• Outros Autores: MOREIRA, Antonio Luciano Seabra, MOUTINHO, Daniel Joaquim da Conceição, DIAS FILHO, José Marcelino da Silva, ROCHA, Otávio Fernandes Lima da, SPINELLI, José Eduardo
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFPA
• Texto Completo: http://repositorio.ufpa.br/jspui/handle/2011/6998
• topic: Colunar equiaxial de transição; Solidificação; Parâmetros térmicos; Condições do estado instável; Ligas Al-Si

Experiments were conducted to investigate the influence of thermal parameters on the columnar to equiaxed transition during the horizontal unsteady-state directional solidification of Al-Si alloys. The parameters analyzed include the heat transfer coefficients, growth rates, cooling rates, temperature gradients and composition. A combined theoretical and experimental approach is developed to determine the solidification thermal variables considered. The increasing solute content in Al-Si alloys was not found to affect significantly the experimental position of the CET which occurred for cooling rates in the range between 0.35 and 0.64 K/s for any of three alloy compositions examined. A comparative analysis between the results of this work and those from the literature proposed to analyze the CET during upward vertical solidification of Al-Si alloys is reported and the results have shown that the end of the columnar region during horizontal directional solidification is abbreviated as a result of about six times higher thermal gradient than that verified during upward unidirectional solidification of alloys investigated.