Physical Features of Advanced Monocrystals Growth under Space Flight Conditions

Michael Shoikhedbrod

Abstract

In terrestrial conditions, gravitational forces impede the production of materials with uniform distribution of components and phases. Strong thermo gravitational unsteady convection leads to instability of crystal growth parameters and limits the possibility of obtaining crystals with a high degree of homogeneity and structure with ideal parity. The first results of growing crystals under microgravity conditions showed the fundamental possibility of obtaining more perfect crystals due to the absence of gravitational convection. However, under microgravity conditions in melts, new opportunities appear for convective processes of a non-gravitational type - Marangoni convection, as well as (in the presence of residual gravity) small thermo gravitational processes leading to the problem of obtaining advanced homogeneous crystals. Another problem is the presence, in contrast to terrestrial conditions, (absence of the Archimedes force) of gas inclusions in melts and crystalline solutions, which also leads to the impossibility of obtaining advanced homogeneous crystals. The article presents the physical features of advanced monocrystals growth in space flights, which consist in the fact that in order to achieve the main goal of advanced monocrystals growth in space flight, the process of vibro-turbulization is used to degassing the crystalline solution or melt and intensive mixing of their components.