Grain boundary component in W-Ga composites: a way towards skeleton   structures
  Nanostructured materials consist of crystalline and grain boundary components. In the simplest case, both components are chemically identical. Here, we present the results of a study of a system consisting of a crystalline component built by A atoms (tungsten) and a grain boundary component of B atoms (gallium). Within this system, component B is in a disordered state. Most likely it exhibits an 'amorphous-like' structure, and coats the tungsten crystals uniformily with a constant thickness, thus forming a Ga skeleton structure. The non-crystalline gallium seems to undergo no first order structural phase transitions, e.g., no first order melting transition was noted when the composit was below, at or above the equilibrium melting point of Ga. The properties of gallium as grain boundary component differ significantly from those of crystalline and amorphous bulk gallium. 
W.Krauss and H.Gleiter