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

DOI: 10.1016/j.actamat.2014.05.035 DOI Help

Authors: Biao Cai (University of Manchester) , Shyamprasad Karagadde (University of Manchester) , Lang Yuan (GE Global Research Center, Niskayuna, NY, USA) , James Marrow (University of Oxford) , Thomas Connolley (Diamond Light Source) , Peter Lee (University of Manchester)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Acta Materialia , VOL 76 , PAGES 371 - 380

State: Published (Approved)
Published: June 2014
Diamond Proposal Number(s): 7604

Open Access Open Access

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.

Journal Keywords: Aluminium Alloys; Bending; Compression; Copper Alloys; Dendrites; Fragmentation; Interlocks; Microstructure; Solids; Strains; Tomography; X Radiation

Subject Areas: Materials, Technique Development
Collaborations: Diamond Manchester

Instruments: I12-JEEP: Joint Engineering, Environmental and Processing