Complex eutectic growth and Bi precipitation in ternary Sn-Bi-Cu and Sn-Bi-Ag alloys

Autor(es)

Silva, Bismarck Luiz ; Garcia, Amauri ; Spinelli, Jose Eduardo

• Tipo de documento: Artigo Científico
• Fonte: Journal of Alloys and Compounds; v. 691, p. 600-605, JAN 15 2017.
• Citações Web of Science: 18

Resumo

Sn-34 wt%Bi, Sn-34 wt%Bi-2wt%Ag and Sn-34 wt%Bi-0.7 wt%Cu alloys have been directionally solidified (DS) under a broad range of solidification cooling rates. Microstructures have been characterized with emphasis on both eutectic growth and precipitation of Bi within the beta-Sn dendritic matrix. The eutectic growth, for all alloys examined, is shown to be associated with the coexistence of coarse and fine lamellar structures with different length-scale of lamellar spacing (lambda). Experimental growth relations of l vs. the cooling rate have been proposed. The length-scale of the lamellae in the fine eutectic ranges from 0.8 to 2.5 mm while in the coarse eutectic from 1.8 to 4.0 mm. Taking as reference the Sn-Bi alloy, both the spacing between Bi precipitates (lambda(p)) and the fine eutectic spacing (lambda(fine)) increase with Cu and Ag additions, whereas lambda(coarse) remains roughly unaltered. Both ternary Sn-Bi-Ag and Sn-Bi-Cu alloys are shown to have worse distributions of both lamellae in the fine eutectic and of precipitates within Sn-rich dendrites, which resulted in decrease in hardness. (C) 2016 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 15/11863-5 - Parâmetros da microestrutura de solidificação de ligas multicomponentes Al-Si-Cu, Sn-Bi-Sb e Zn-Sn-Cu e propriedades mecânicas decorrentes
• Beneficiário: José Eduardo Spinelli
• Linha de fomento: Auxílio à Pesquisa - Regular
• Processo FAPESP: 13/08259-3 - Desenvolvimento microestrutural e do comportamento mecânico de ligas alternativas de soldagem Sn-Bi-Cu e Sn-Bi-Ag
• Beneficiário: Bismarck Luiz Silva
• Linha de fomento: Bolsas no Brasil - Doutorado