Coupling between elastic strains and phase transition in dense pure zirconia polycrystals

Abstract

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Phase transition and twinning in polycrystals probed by in situ high temperature 3D reciprocal space mapping

“…12 We have recently demonstrated that this method can be used even at very high temperatures. 13,14 This paper aims to extend the 3D-RSM method to the in situ observations of solid-state phase transitions that occur in polycrystals at high temperatures. The potential of this approach is illustrated by examining two successive phase transitions in dense polycrystals of pure zirconia.…”

“…This corresponds to 2 Â 2 Â 2 ¼ 8 possibilities, i.e., eight crystallographic variants. Considering the respective crystal lattice orientation among c, t, and m phases 25 and the lattice parameters of each phase, 14 one can easily compute the coordinate of all RLNs in the reciprocal space, taking here Q x , Q y , and Q z parallel to the axes of the parent cubic lattice. This is illustrated for one of the tetragonal variants, and the locations of the eight associated monoclinic RLNs generated by the t !…”

“…After cooling, the material consists in large areas of pure zirconia embedded in silica-based glass. These sub-millimeter volume regions contain a very large number of nanometer-sized crystals 14,26,27 (e.g., see the TEM images shown Fig.…”

LaueNN: neural network based hkl recognition of Laue spots and its application to polycrystalline materials

“…This case study demonstrates the capability of the LaueNN model to resolve complex Laue images acquired on lowsymmetry monoclinic zirconia polycrystalline material that has undergone the solid-state martensitic phase transition (from tetragonal to monoclinic) and thus exhibits a very subdivided and complex microstructure with microcracks (Ors et al, 2021;Guinebretie `re et al, 2022). Low-symmetry crystal Laue patterns are often difficult to index using the conventional approach described in Section 2.1, as screening of a large number of spots is necessary to ensure a result.…”

Laue microdiffraction on polycrystalline samples above 1500 K achieved with the QMAX-µLaue furnace

“…A crystal structure can be recognized in this Laue pattern, although the image is crowded with many (thousands) small spots. Such crowding of Laue peaks comes from the fact that the actual m-ZrO 2 crystals are nanometric in size (Guinebretie `re et al, 2022), i.e. several orders of magnitude smaller than the gauge volume size (at 17.5 keV, the penetration depth of X-rays into zirconia is �150 mm), and therefore a single Laue image gathers diffraction spots from a very large number of individual crystals.…”