Concept of solidification of casting metals

- A molten metal in which high energy state. As the melt cools, it loses energy to form crystals

- Since heat loss walls near the model faster than anywhere else, the first crystallites form submicroscopic metal called nuclei here.

- Melt experience difficulty starting crystallites have no impurity crystallization nuclei to start.

- However in such conditions and form crystals melt undercools so nucleus or seed.

- Nuclei formed as above tends to grow at the second stage of solidification.

- The crystal growth proceeds with energy released by melting crystal interface. Crystal growth occurs on dendritic manner.

- Dendritic growth takes place at the evolution of small arms on the original branches of individual dendrites.

- Gives the resulting solid dendrites grain.
(a) a Slow cooling the dendrites grow long while rapid cooling causes short dendrite growth.
(b) Since the end be dendrites grain, slow cooling results in large grain structure and rapid cooling in small grains in the metal structure solidified.

- As solidification proceeds, growing more and more weapons on existing dendrite and also dendrites more and more the form until all crystallized melt.

- Dendrite Growth weapons because metal atoms attach themselves to solid dendrite.

- Smashing arrange themselves into three-dimensional pattern is repeated many times during the crystal growth.

- The unit of repetition is called unit cells. Unit cells arrange themselves in straight lines.

- Just so lines in a geometric pattern formed right angles to each other to produce dendritic structure.

- Dendrite growth that out until they contact the dendrite nearby and generate grain boundaries, ie boundaries between crystals or grains

- Quiet probably the army dendrite concentrated and ultimately can solid crystal or grain stay no expression on dendritic growth.