Analysis of the 355 aluminium alloy microstructure for application in thixoforming

Leandro Cássio de Paula, Shun Tokita, Kota Kadoi, Hiroshige Inoue, Eugênio José Zoqui

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

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.

Original languageEnglish
Title of host publicationSemi-Solid of Alloys and Composites XV
EditorsQiang Zhu, Xiao Gang Hu, Ahmed Rassili, Stephen P. Midson
PublisherTrans Tech Publications Ltd
Pages277-282
Number of pages6
ISBN (Print)9783035713732
DOIs
Publication statusPublished - 2019
Externally publishedYes
Event15th International conference on Semi-Solid Processing of Alloys and Composites, S2P 2018 - Shenzhen, China
Duration: 2018 Oct 222018 Oct 24

Publication series

NameSolid State Phenomena
Volume285 SSP
ISSN (Print)1012-0394
ISSN (Electronic)1662-9779

Conference

Conference15th International conference on Semi-Solid Processing of Alloys and Composites, S2P 2018
CountryChina
CityShenzhen
Period18/10/2218/10/24

Keywords

  • Aluminium Alloys
  • In situ Microstructure Observation
  • Microstructure
  • Ultrasonic Melt Treatment (UST)

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Materials Science(all)
  • Condensed Matter Physics

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