In situ Synchrotron Tomographic Quantification of Semi-solid Properties of Aluminum-Copper alloys

  • Biao Cai

Student thesis: Phd


Semi-solid deformation mechanisms are important in a range of manufacturing and natural phenomena, which range from squeeze casting to magma flows. In this thesis, using high speed synchrotron X-ray tomography and a bespoke precision thermo-mechanical rig, a four dimensional (3D plus time) quantitative investigation was performed to study the mechanical / rheological behavior of semi-solid Al-Cu alloys. Various deformation techniques, namely, isothermal semi-solid compression, extrusion and indentation were used. The time-resolved dynamic 3D images were analyzed with the help of novel image quantification techniques including digital volume correlation and image-based simulations of fluid flow. The quantified dynamics at a microstructural scale was then linked with macroscopic mechanical properties. The qualitative and quantitative analyses revealed a range of important semi-solid micromechanical mechanisms including the occurrence and effects of dilatancy, associated liquid flow through the equiaxed microstructure, intra-dendritic deformation, and strain localization during semi-solid deformation, not only shedding new insights into the mechanisms of deformation-induced solidification defect formation (solute segregation, porosity and hot tearing) of semi-solid alloys at both a macroscopic and microscopic level, but also providing benchmark cases for semi-solid deformation models and theories. The experimental methodology, techniques and analysis procedures developed in this thesis are generic in nature and can be applied to a wide range of research fields.
Date of Award31 Dec 2015
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorPeter Lee (Supervisor)


  • Alloy
  • X-ray tomography
  • Semi-solid deformation
  • Solidification

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