Self-Similar Porosity In Quasicrystals

Abstract

Single grains of real quasicrystals have been investigated using X-ray imaging techniques at a third-generation synchrotron radiation source (ESRF). Facetted microholes have been observed. The experimental results are discussed with reference to a description of the quasicrystal structure in terms of overlapping atomic clusters (self-similar packing or random covering modifications). Relations between holes and quasicrystal formation are also discussed.

Extended investigation of porosity in quasicrystals by synchrotron X-ray phase contrast radiography—I: In icosahedral AlPdMn grains

“…The first one is the condensation of thermal vacancies [6], the second one invokes a structural model which considers porosity as an intrinsic feature [7]. Currently the available data on porosity in QCs, which were obtained on a small number of samples, are consistent with both contradictory hypotheses.…”

The Influence of Growth Rate on Porosity in Al-Pd-Mn Icosahedral Quasicrystals.

“…Additional work by Beeli et al confirmed that pore size and spacing corresponded to diffusion models [4]. Two other hypotheses regarding the origin of porosity were based on quasicrystalline structural arguments [5,6]. The self-similar model proposes that porosity develops from specifically located vacancies that are inherent in the quasicrystal structure [5].…”

“…The self-similar model proposes that porosity develops from specifically located vacancies that are inherent in the quasicrystal structure [5]. A modification of the selfsimilar model, the random covering theory, maintains the inherent and specifically located vacancies but increases the ability for deviation from the perfect arrangement by reducing the strict scaling laws [6].…”

Extended investigation of porosity in quasicrystals by synchrotron X-ray phase contrast radiography: Part II, in grains of other alloys and structures than AlPdMn

“…This hypothesis stated that pores of determined sizes are structural elements necessary for the existence of icosahedral phases [11]. Note, however, that the present results are only valid for pores larger than a few microns, since the experimental resolution does not permit to observe contrasts stemming from smaller pores.…”