Transgranular liquation cracking of grains in the semi-solid state

Research output: Contribution to journalArticlepeer-review


  • S. Karagadde
  • P. D. Lee
  • J. L. Fife
  • M. A. Azeem
  • K. M. Kareh
  • C. Puncreobutr
  • D. Tsivoulas
  • T. Connolley
  • R. C. Atwood

Colleges, School and Institutes


Grain refinement via semi-solid deformation is desired to obtain superior mechanical properties of cast components. Using quantitative in situ synchrotron X-ray tomographic microscopy, we show an additional mechanism for the reduction of grain size, via liquation assisted transgranular cracking of semi-solid globular microstructures. Here we perform localized indentation of Al-15wt.%Cu globular microstructures, with an average grain size of ∼ 480μm, at 555 deg;C (74% solid fraction). Although transgranular fracture has been observed in brittle materials, our results show transgranular fracture can also occur in metallic alloys in semi-solid state. This transgranular liquation cracking (TLC) occurs at very low contact stresses (between 1.1 and 38 €‰MPa). With increasing strain, TLC continues to refine the size of the microstructure until the grain distribution reaches log-normal packing. The results demonstrate that this refinement, previously attributed to fragmentation of secondary arms by melt-shearing, is also controlled by an additional TLC mechanism.


Original languageEnglish
Article number8300
JournalNature Communications
Early online date10 Sep 2015
Publication statusPublished - 1 Dec 2015


  • Mechanical properties, Metals and alloys