Metallic glasses possessing a fractal short-range and a homogeneous long-range structures – a dimensionality crossover at an intermediate length scale

Figure caption: In situ diffraction and volume results. (A) Three-dimensional reconstructed sample volumes from in situ transmission x-ray microscopy data. (B) In situ x-ray diffraction data with increasing pressure.
Figure caption: In situ diffraction and volume results. (A) Three-dimensional reconstructed sample volumes from in situ transmission x-ray microscopy data. (B) In situ x-ray diffraction data with increasing pressure.

Metallic glasses earn their name from a lack of long-range atomic order and the absence of typical defects, such as dislocations, and exhibit exotic material properties. The incomplete understanding of atomic-level structure in glassy materials has made it challenging to capture the physics of their response to mechanical deformation. Recent HPCAT x-ray diffraction experiments, together with x-ray tomography and molecular dynamics simulations, revealed a crossover between fractal short-range (<2 atomic diameters) and homogeneous long-range structures in metallic glasses. A specific class of fractal, the percolation cluster, is proposed to explain the structural details for several metallic-glass compositions. The results is recently published in Science. (Chen et al, Science, 349, 1306-1310, 2015)