12 Questions
What is the primary purpose of ensuring the interstices of the dendrites are well-fed with melt during solidification?
To prevent interdendritic shrinkage cavities from forming.
What is the region between the tips of the dendrites and the last solidifying liquid referred to as?
Mushy or pasty zone.
How can electromagnetic stirring of the melt prevent dendritic formation?
By preventing dendric formation, resulting in a fine-grained and equiaxed structure.
What is the origin of equiaxed grains in the centre of the ingot?
Melted-off dendritic side-arms.
Why is a fine-grained equiaxed structure preferred for technical use?
Because it is stronger and more ductile.
What factors favor the development of the equiaxed zone?
Low pouring temperature, moulds of low thermal conductivity, and the presence of alloying elements.
What is the primary difference between the solidification of pure metals and commercially pure metals?
Commercially pure metals contain impurities that change the characteristics of solidification from pure-metal to alloy behavior.
What happens to the concentration gradient ∆C when C0 becomes equal to Cαθ during the growth of cementite in ferrite?
The concentration gradient ∆C ceases to fall, and the diffusion of carbon ceases.
What is the partitioning coefficient (K) a measure of?
The difference in solubility of a solute in two immiscible or slightly miscible phases that are in equilibrium or in contact with each other.
What is the result of the partitioning of carbon during the phase transformation from ferrite to cementite?
The solidification temperature of the melt changes, becoming lower at the interface where the concentration of carbon is high, and higher at the core of the liquid where the concentration of carbon is lower.
What is the primary cause of the increase in undercooling during alloy solidification?
The compositional change, specifically the enrichment of the liquid with the low-melting-point element B, which lowers the melting point.
What is the result of the changing composition of the liquid during eutectic solidification?
A changing solidification temperature from the solid-liquid interface to the core of the liquid.
Learn about the solidification process of ingots, including the formation of dendritic structures and the importance of the mushy zone in preventing interdendritic shrinkage cavities. Understand the impact of temperature gradient and non-equilibrium freezing range on the solidification process.
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