Transient Unidirectional Solidification, Microstructure and Intermetallics in Sn-Ni Alloys

Author(s)

Clarissa Barros da Cruz ^[1] ; Rafael Kakitani ^[2] ; Marcella Gautê Cavalcante Xavierb ^[3] ; Bismarck Luiz Silva ^[4] ; Amauri Garcia ^[5] ; Noé Cheung ^[6] ; José Eduardo Spinelli ^[7]

Affiliation

^[1] Universidade de Campinas - UNICAMP. Departamento de Engenharia de Materiais e Manufatura - Brasil

^[2] Universidade de Campinas - UNICAMP. Departamento de Engenharia de Materiais e Manufatura - Brasil

^[3] Universidade Federal de São Carlos - UFSCar. Departamento de Engenharia de Materiais - Brasil

^[4] Universidade Federal do Rio Grande do Norte - UFRN. Departamento de Engenharia de Materiais - Brasil

^[5] Universidade de Campinas - UNICAMP. Departamento de Engenharia de Materiais e Manufatura - Brasil

^[6] Universidade de Campinas - UNICAMP. Departamento de Engenharia de Materiais e Manufatura - Brasil

^[7] Universidade Federal de São Carlos - UFSCar. Departamento de Engenharia de Materiais - Brasil

• Document type: Journal article
• Source: MATERIALS RESEARCH-IBERO-AMERICAN JOURNAL OF MATERIALS; v. 21, 2018-04-12.

Abstract

The present research work examines the microstructural arrangements formed during the transient solidification of eutectic Sn-0.2wt.%Ni and hypereutectic Sn-0.5wt.%Ni alloys. Also, it examines their respective correlations with solidification thermal parameters: eutectic growth rate (VE) and eutectic cooling rate (ṪE); length scales of matrix and eutectic phases: microstructural spacings and the corresponding tensile properties: ductility and strength. Both alloys were directionally solidified upwards under unsteady-state regime, and characterized by optical and scanning electron microscopy. Concerning the hypereutectic Sn-0.5wt.%Ni, the increase in Ni content is shown to influence both thermal behavior and cellular spacing (λC). The NiSn4 intermetallics is present in the eutectic mixture of both alloys, whilst in the Sn-0.5wt.%Ni alloy the primary phase has been identified by SEM-EDS as the Ni3Sn4 intermetallics. A β-Sn morphological cellular/dendritic transition occurs in the 0.2wt.%Ni eutectic alloy for ṪE> 1.2K/s. Despite that, regular cells in the hypereutectic alloy (0.5wt.%Ni) turns into plate-like cells for ṪE> 1.4K/s. If considered a reference cellular spacing about 20μm (i.e.,λ(c-1/2=0.22), the samples associated with the Sn-0.5wt.%Ni alloy are shown to be associated with higher tensile strengths, but much lower ductility as compared with the corresponding results of the eutectic alloy. (AU)

• FAPESP's process: 17/15158-0 - Characterization of microstructure and properties in the evaluation of alloys for thermal interface contact
• Grantee: Amauri Garcia
• Support Opportunities: Regular Research Grants
• FAPESP's process: 15/11863-5 - Microstructure evaluation of ternary Al-Si-Cu, Sn-Bi-Sb and Zn-Sn-Cu and its correlations with mechanical properties
• Grantee: José Eduardo Spinelli
• Support Opportunities: Regular Research Grants
• FAPESP's process: 17/12741-6 - Application of experimental solidification techniques, characterization of microstructure and properties in the evaluation of eutectic and hypereutectic Al-base and Zn-base alloys
• Grantee: José Eduardo Spinelli
• Support Opportunities: Regular Research Grants
• FAPESP's process: 16/18186-1 - Microstructural evolution and mechanical and wear resistances of ternary Al-Bi-Si and Al-Bi-Ni alloys unidirectionally solidified
• Grantee: José Marcelino da Silva Dias Filho
• Support Opportunities: Scholarships in Brazil - Post-Doctoral