Effect of solution time in T6 heat treatment on microstructure and hardness of a directionally solidified Al-Si-Cu alloy

Author(s)

Costa, Thiago A. ^[1] ; Dias, Marcelino ^[1] ; Gomes, Laercio G. ^[2] ; Rocha, Otavio L. ^[2] ; Garcia, Amauri ^[1]

Affiliation

^[1] Univ Estadual Campinas, UNICAMP, Dept Mfg & Mat Engn, BR-13083860 Campinas, SP - Brazil

^[2] IFPA, Fed Inst Educ Sci & Technol Para, BR-66093020 Belem, PA - Brazil

• Document type: Journal article
• Source: Journal of Alloys and Compounds; v. 683, p. 485-494, OCT 25 2016.
• Web of Science Citations: 21

Abstract

An experimental investigation on the role of solution time during the T6 heat treatment on the scale of the secondary dendrite arm spacing (lambda(2)), morphology and distribution of Si particles and Al2Cu intermetallics and the resulting effect on microhardness of Al-5.5 wt% Si-3.0 wt% Cu alloy samples is performed. A directionally solidified (DS) casting was previously obtained using a water-cooled apparatus, which permitted a wide range of cooling rates ((T) over dot) to be associated with samples having quite different microstructural parametric features. An experimental growth law relating lambda(2) to (T) over dot is proposed. The T6 heat treatment was then carried out on the DS samples for different solution times: 8 h and 5 h at 490 +/- 2 degrees C, followed by quenching in warm water (60 +/- 2 degrees C), ageing for 5 h at 155 +/- 2 degrees C and air-cooling. The microstructure characterization (optical and scanning electron microscopies) has shown that lambda(2) was only affected (when compared with those of the DS casting samples) when the solution time increased from 5 h to 8 h. In contrast, significant influences on the morphology and distribution of both Si and Al2Cu particles are shown to occur. The highest hardness is shown to be associated with a sample subjected to the 5 h treatment, having lowest lambda(2) and appropriate modification of Si and Al2Cu particles. (C) 2016 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 13/23396-7 - Effects of solidification MicrostructureParameters of Aluminum-based multicomponent alloys (Al-Mg-Si; Al-Sn-Cu; Al-Zn-Mg) on the resistances to Corrosionand tribocorrosion degradation
• Grantee: Amauri Garcia
• Support Opportunities: Regular Research Grants
• FAPESP's process: 13/09267-0 - Microstructural evolution in the transient solidification of monophasic and peritectic Sn-Sb solder alloys (and Sn-Sb-X) and in solder/substrate interfacial layers
• Grantee: José Marcelino da Silva Dias Filho
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 14/50502-5 - Interrelation of thermal and microstructural solidification parameters and corrosion/tribocorrosion behavior of alloys for tribological, biomedical and solder applications
• Grantee: Amauri Garcia
• Support Opportunities: Regular Research Grants