Precipitation of stable icosahedral quasicrystal phase in a Mg-Zn-Al alloy

0556293 - FZÚ 2023 RIV GB eng J - Journal Article
Singh, A. - Hiroto, T. - Ode, M. - Takakura, H. - Tesař, Karel - Somekawa, H. - Hara, T.
Precipitation of stable icosahedral quasicrystal phase in a Mg-Zn-Al alloy.
Acta Materialia. Roč. 225, Feb. (2022), č. článku 117563. ISSN 1359-6454. E-ISSN 1873-2453
Institutional support: RVO:68378271
Keywords : magnesium alloys * quasicrystals * precipitation * transmission electron microscopy * in situ X-ray diffraction
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 9.4, year: 2022
Method of publishing: Limited access
https://doi.org/10.1016/j.actamat.2021.117563

Precipitation of a stable quasicrystalline i-phase has been discovered in a Mg-6Zn-3Al (wt%, ZA63) magnesium alloy, possibly a first involving a stable i-phase. Dissolution of i-phase solidified at grain boundaries leads to precipitation in the Mg-matrix during. Phase transformation, nucleation characteristics, morphology and interfaces with the matrix have been studied. Differential scanning calorimetry (DSC) and in-situ X-ray diffraction (XRD) showed dissolution and precipitation of i-phase during heating and cooling cycles, forming a hysteresis between about 250 and 325 C. The quasilattice parameter of i-phase was calculated to be 5.17 Å at room temperature, close to the c-parameter 5.18 Å of the Mg-matrix. At dissolution/nucleation, the diffraction peaks of i-phase were sharper, (quasi)lattice constants become equal to each other (5.22 Å) and the lattice strain in the matrix was minimized. The precipitates were faceted sharply on fivefold, twofold and threefold planes.
Permanent Link: http://hdl.handle.net/11104/0330580