Material Science Solidificaiton compare the required underco

Material Science, Solidificaiton:

compare the required undercooling temperature, critical nuclei size, energy barrier for homogeneous and heterogeneous nucleation.

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Solution

>> Critical Nuclei radius is same for both homogeneous and heterogeneous nucleation, while the critical nucleus volume is smaller for heterogeneous nucleaation

>> Energy Barrier

As Hetregeneous nucleation occurs on one side, then due to directional solidification or due to presence of a surface already, energy barrier required for nucleation is REDUCED in case of heterogeneous nucleation.

>> Undercooling Temperature

High Undercooling (and so cooling to more lower temperature) is required for hu=omogeneous nucleation while due to less energy barrier, this undercooling required is less in heterogeneous nucleation