INVESTIGATION OF LIQUID PHASE STRUCTURE, COPPER ALLOY CRYSTALLIZATION AND STRUCTURE FORMATION PROCESSES

Abstract

The effect of alloying elements (Sn, Al, Si, Mn, Zn, Ni, As) on the morphology of the liquid phase, crystallization and structure formation processes of copper alloys (Cu + alloying elements) has been investigated. All the investigated alloying elements other than nickel are revealed to rise the degree of compaction (shrinkage) of the melt (ΔJliq) and the coefficient of thermal contraction (αliq) of liquid copper alloy because of the weakening of the binding forces between the atoms of copper and alloying elements (FCu-Cu > FCu-X). Nickel reduces the liquid state parameters due to increased binding forces between Cu and X atoms (FCu-X > > FCu-Cu), as evidenced by increase in crystallization temperature of α-solid solution. All the above alloying elements, other than Ni, lower the temperature of α-solid solution crystallization start (tliq) and end (ts) and extend the temperature range of α-solid solution crystallization tliq–ts. Copper alloys have a high degree of melt compaction during crystallization (ΔJcr): the denser the alloying element (higher density), the greater the degree of compaction ΔJcr. It is most valid for Ni and least valid for Al and Si. Up to the certain content, all the alloying elements reduce the structural components to small size (α-solid solution and eutectoid).