Preparation of Large-Volume, Stable Composition Polycrystalline Mixture of Binary Solid Solutions

Abstract

Here, a new method of preparing a polycrystalline mixture with a large volume of stable composition from binary solid solutions is presented. For this purpose, several holes of small diameter (0.5–1 mm) are opened at the bottom of the quartz pot prepared for melting the alloy. The upper end of the mold made of quartz, according to the geometrical structure of the mixture, is connected to the bottom of the puta in such a way that the holes in the puta remain inside it and both volumes are hermetically connected. Such a “puta-mould” system is fixed in the device in such a way that the template (mould) of the mixture is in a vertical position. Appropriate masses of the components of the solid solution are placed in a crucible and melted under high vacuum conditions. After the molten liquid becomes homogeneous, inert gas with a pressure of 0.5–0.8 atm is injected into the working volume. Due to the pressure force exerted by the gas on the surface of the liquid, it rushes through the holes and fills the mold, where it crystallizes at a high speed. The mold is placed inside a thick-walled, heat-conducting cylinder connected to a running water-cooled body of the lower end unit. This ensures that crystallization occurs at a high speed. Thus, the composition has the same value throughout the prepared mixture. Using the method, an alloy containing 10 at % Si was prepared from the Ge–Si solid solution system. Calculation of the density of samples taken from different parts of the mixture confirmed that the composition was the same throughout the mixture.