Application of synchrotron x-ray microtomography to investigate ductile fracture in Al alloys

Abstract

The in situ high-resolution synchrotron x-ray computed microtomography has been applied to visualize and quantify the ductile fracture process of a notched Al alloy specimen. The three-dimensional (3D) investigation reveals that voids are nucleated, grow and coalesce more easily near the notch front and in the central region of the sample. These voids are mainly associated with Si particles in the eutectic (EU) phase. The 3D packing architecture of particles in the EU region, and the 3D morphology of α phase are also visualized. The feasibility of this technique highlights the potential of its application in the field of micromechanics-based fracture.

Evolution of voids during ductile crack propagation in an aluminium alloy sheet toughness test studied by synchrotron radiation computed tomography

“…Using in-situ tests Qian et al [14] highlight the growth of voids and their coalescence during ductile fracture of a notched specimen geometry via SRCT. Fatigue crack closure phenomena have also been observed and quantified by various researchers [15][16][17][18].…”

Roles of Pre-Existing Hydrogen Micropores on Ductile Fracture

“…1,3) It has been clarified that percentage porosity depend on the hydrogen content in aluminum alloy, 4,5) strongly suggesting that micropores in aluminum alloys are filled with molecular hydrogen. Synchrotron X-ray microtomography has been applied to the observations of high-density micropores, [6][7][8][9][10][11][12] because this technique is especially effective for micropore observation, since micropores are easily filled with abrasive powders during sample preparation processes for observation, such as cutting and polishing.…”

3D Image analysis for evaluating internal deformation / fracture characteristics of materials

“…Considering that 3D-CT image acquisition and reconstruction presently requires about 1 day [11,12], this time seems quite practicable. Table 5 shows comparative results on processing times with different numbers of pores.…”

“…However, 3D-CT images of nano-order resolution have become available recently due to implementation of high-brightness synchrotron radiation and improvement of camera performance [10]. There have been attempts at quantitative analysis of internal deformation by strain-induced displacement of air bubbles inside materials [11,12]. However, it is difficult to extract numerous bubbles and to identify their positions before and after deformation by visual observation.…”