TY - GEN
T1 - Analysis of the 355 aluminium alloy microstructure for application in thixoforming
AU - Paula, Leandro Cássio de
AU - Tokita, Shun
AU - Kadoi, Kota
AU - Inoue, Hiroshige
AU - Zoqui, Eugênio José
N1 - Funding Information:
The authors would like to thank the Brazilian research funding agencies FAPESP (Project 2015/22143-3), CNPq (PQ 304921/2017-3), and CAPES for providing this study with financial support. The authors are also indebted to the Department of Reliability Evaluation & Simulation, Joining and Welding Research Institute, at the Osaka University for their kind support.
Publisher Copyright:
© 2019 Trans Tech Publications, Switzerland.
PY - 2019
Y1 - 2019
N2 - The 355 aluminium alloy is known to have excellent thermodynamic characteristics that render it suitable as a raw material for rheocasting and thixoforming. However, besides the controllable transition from solid to liquid phase, the refined microstructure required in the semisolid range is one of the key factors with a strong influence on the rheology of the material. This paper intends to analyse the in situ behaviour of the microstructure, in terms of morphological change, using high-temperature laser scanning confocal microscopy. The 355 alloy was prepared via conventional casting, and refined with a 30-s exposition via ultrasonic melt treatment (UST-20 Hz, 2 kW). The material was reheated up to the thixoforming target temperature of 595 °C at which it was maintained for 0, 30, 60, 90, and 120 s, after which all the samples were cooled in water. The samples subjected to UST prior to the heat treatment were more refined in terms of microstructural evolution; they exhibited reduction in grain size (~107 ± 16 μm), smallest primary phase particle size (~81 ± 7 μm), and high circularity shape factor (~0.59 ± 0.19 μm). In situ observation methods were employed to analyse evolution mechanisms such as Ostwald ripening and coalescence.
AB - The 355 aluminium alloy is known to have excellent thermodynamic characteristics that render it suitable as a raw material for rheocasting and thixoforming. However, besides the controllable transition from solid to liquid phase, the refined microstructure required in the semisolid range is one of the key factors with a strong influence on the rheology of the material. This paper intends to analyse the in situ behaviour of the microstructure, in terms of morphological change, using high-temperature laser scanning confocal microscopy. The 355 alloy was prepared via conventional casting, and refined with a 30-s exposition via ultrasonic melt treatment (UST-20 Hz, 2 kW). The material was reheated up to the thixoforming target temperature of 595 °C at which it was maintained for 0, 30, 60, 90, and 120 s, after which all the samples were cooled in water. The samples subjected to UST prior to the heat treatment were more refined in terms of microstructural evolution; they exhibited reduction in grain size (~107 ± 16 μm), smallest primary phase particle size (~81 ± 7 μm), and high circularity shape factor (~0.59 ± 0.19 μm). In situ observation methods were employed to analyse evolution mechanisms such as Ostwald ripening and coalescence.
KW - Aluminium Alloys
KW - In situ Microstructure Observation
KW - Microstructure
KW - Ultrasonic Melt Treatment (UST)
UR - http://www.scopus.com/inward/record.url?scp=85059937150&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85059937150&partnerID=8YFLogxK
U2 - 10.4028/www.scientific.net/SSP.285.277
DO - 10.4028/www.scientific.net/SSP.285.277
M3 - Conference contribution
AN - SCOPUS:85059937150
SN - 9783035713732
T3 - Solid State Phenomena
SP - 277
EP - 282
BT - Semi-Solid of Alloys and Composites XV
A2 - Zhu, Qiang
A2 - Gang Hu, Xiao
A2 - Rassili, Ahmed
A2 - Midson, Stephen P.
PB - Trans Tech Publications Ltd
T2 - 15th International conference on Semi-Solid Processing of Alloys and Composites, S2P 2018
Y2 - 22 October 2018 through 24 October 2018
ER -