In situ synchrotron tomographic quantification of granular and intragranular deformation during semi-solid compression of an equiaxed dendritic Al–Cu alloy

B. Cai, S. Karagadde, L. Yuan, T.j. Marrow, T. Connolley, P.d. Lee

Research output: Contribution to journalArticlepeer-review

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Abstract

Semi-solid deformation mechanisms are important in a range of manufacturing and natural phenomena, which range from squeeze casting to magma flows. Using fast synchrotron X-ray tomography and a bespoke precision thermomechanical rig, we performed a four-dimensional (3-D plus time) quantitative investigation of the granular behaviour of equiaxed dendritic three-phase materials. This methodology produced new insights into the formation of damage during the isothermal semi-solid compression (∼30% liquid fraction) of an Al–15 wt.%Cu alloy at both a macroscopic and microscopic level. Grain rearrangements, such as translation and rotation, were observed and lead to local dilatancy. The resulting flow of Cu-rich intergranular liquid into the dilated interstices gave rise to a local increase in liquid fraction, followed by rapid void growth above a critical axial strain of −6.4%. The local normal and shear strain distributions were quantified using digital volume correlation, identifying dilatant shear bands. At a microstructural level, the individual grains were also seen to undergo intragranular deformation, leading to bending and fragmentation of dendrites as grains interlock.
Original languageEnglish
Pages (from-to)371-380
Number of pages10
JournalActa Materialia
Volume76
DOIs
Publication statusPublished - 19 Jun 2014

Keywords

  • Semi-solid deformation
  • Granular mechanics
  • Microstructural response
  • Dilatancy
  • Hot tearing

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