Physical Modifying Effects and Their Influence on the Crystallization of Cast Alloys

Abstract

Main notions on the influence of modifying physical effects (vibration, ultrasound, electromagnetic stirring, thermal-temporal treatment) on the crystallization of cast alloys are generalized. It is revealed with the help of mathematic calculations and experimental investigations that the crystallization and structure formation of cast alloys can be largely determined by the technology of treatment by physical effects during smelting and casting. Physical effects on the crystallizing melt lead to its strong turbulization and mixing, which decreases the temperature and concentration gradients in the melt, eliminates overheating of the liquid phase relative to the solidus temperature, and breaks off the dendrites, which are good crystallization seeds for the entire melt bulk. The evaluation of the dendritic growth during the crystallization showed that dividing the dendrite grains under the physical effects to the melt withstands to their coarsening. Physical effects lead to the bulk crystallization with equiaxial grains without the formation of the columnar structure. Physical modifying effects promote an increase in the quality of fabricated alloys and casts made of them with the proviso of their rational use.