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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Transition from high cooling rate cells to dendrites in directionally solidified Al-Sn-(Pb) alloys

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Author(s):
Oliveira, Ricardo [1] ; Costa, Thiago A. [2] ; Dias, Marcelino [1] ; Konno, Camila [1] ; Cheung, Noe [1] ; Garcia, Amauri [1]
Total Authors: 6
Affiliation:
[1] Univ Estadual Campinas, UNICAMP, Dept Mat & Mfg Engn, BR-13083860 Campinas, SP - Brazil
[2] Fed Inst Educ Sci & Technol Para, IFPA, BR-66093020 Belem, PA - Brazil
Total Affiliations: 2
Document type: Journal article
Source: MATERIALS TODAY COMMUNICATIONS; v. 25, DEC 2020.
Web of Science Citations: 0
Abstract

The preprogramming of the solidification cooling rate during casting of some Al-based bearing materials, has been used to achieve microstructural patterns conducive to better wear responses. For Al-Sn castings, improvements in the wear resistance were reported to occur when higher amounts of Sn remained segregated in the spacings of the dendritic Al-rich matrix. In this sense, a cellular microstructure could be more adequate since the segregated Sn would be contained along the cells boundaries and not spread through the interstices of multiple dendritic arms. This study investigates a range of Al-xSn alloys compositions (x = 1, 2.6, 7.5, 9, 10 wt.%) and an Al-(9 wt.%)Sn-(1 wt.%Pb), with a view to determining the ranges of Sn concentrations and solidification cooling rates ((T) over dot) for which high cooling rate cells are stable, as well as the reverse cellular/dendritic transition. For (T) over dot from 1 to 40 K/s, it is shown that for Al-Sn alloys having Sn < 7.5 wt.% the morphology of the Al-rich matrix is fully cellular and for Sn > 10 wt.% it is completely dendritic. The reverse transition from high cooling rate cells to dendrites is shown to occur for the Al-9 wt.%Sn alloy, with (T) over dot < 3.3 K/s resulting in a dendritic microstructure and (T) over dot > 6 K/s in a fully cellular Al-rich matrix. The Al-9 wt.%Sn-1 wt.%Pb ternary alloy casting also exhibits a reverse cellular/dendritic transition, with dendrites occurring also for (T) over dot < 3.3 K/s and cells for (T) over dot > 8 K/s. (AU)

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