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1. http://www.yosh.ac.il/research/mmt/
   

The problem of amorphous powder consolidation by thermal spraying methods is not easy to solve for at least the two reasons. On the one hand, the amorphous must be heated to the temperature, which provides good adhesion of the powder particles to some substrate materials, and cohesion between the amorphous particles. On the other hand, amorphous particles being heated to certain temperature (crystallization temperature) undergoes amorphous-to-crystalline solid transition, and consequently loose their properties ascribed to their amorphous structure.

The problem of glass transition in amorphous media has been the subject of much theoretical and experimental investigation recently. In spite of that exhausting understanding of the phenomenon was not attained yet. Standard identification of glass transition temperature T_g is based on calorimetric experiments. At the same time analysis of transport coefficients and scattering experiments indicate the existence of a critical temperature T_c, located above T_g in the region of the supercooled liquid state (1). Near this temperature the dynamic crosses over from the behavior, which is typical for a normal liquid to that which is characteristic for a glass.

Theoretical coupling mode approach, based on the theory of liquids predicts critical temperature T_c located at 50 to 100 degrees K above the calorimetric glass transition temperature (2). Alternatively the Vogel-Fulcher law describes the viscous flow as a thermally activated process, and the Vogel-Fulcher temperature is found 50 to 100 K below T_g. Thus one explanation postulates the important changes at a temperature above T_g and the other at a temperature well below T_g. And neutron scattering data, obtained with liquid and glassy selenium, presented by Buchenau and Zorn (3) demonstrate that solidlike structure of the liquid, based on single-particle approach is more relevant to experimental data.

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