Crystallization features of casting alloys

Abstract

It has been shown that elementary crystal lattices of basic phases and oxides of casting alloys do not satisfy the principle of structural and dimensional correspondence. Formation of crystallization centers during solidification of casting alloys is a nanostructured process. The main demodifying element in melt crystallization is adsorbed hydrogen. It prevents the integration of nanocrystals into the nucleus of crystallization of the main phases of casting alloys. When the melt overheats, adsorption and desorption of hydrogen atoms occur. The predominance of one of these processes explains the features of crystallization of cast‑ ingalloys. Prior to critical superheating of the melt, the adsorption of hydrogen atoms prevails. As a result, molds with an unmodified structure are formed. When the melt overheats above the critical one, the process of desorption of hydrogen atoms prevails. As a result, molds with a modified structure are formed.

Keywords

• casting alloys
• crystallization
• nanocrystals
• main phases
• oxides
• adsorbed hydrogen
• melt overheating