Question

Write three differences between homogeneous and heterogeneous equilibrium.

Answer 1

Differences between homogeneous and heterogeneous equilibrium.

Homogeneous Nucleation	Heterogeneous nucleation
Nucleation takes place without presence (Help)  any impurity atoms.	Nucleation takes place in the presence of impurity atoms.
It is an ideal case of nucleation and occurs in pure metal solidification.	It is found in actual practice and occurs in all metals and alloys
Nucleation may be initiated at any site within the liquid melt simultaneously.	Nucleation is initiated on substrate (impurity) surfaces i.e.its initiation is not simltancous.
This require higher degree of suprecooling	This requires lower degree of supercooling
It is a slower process and hence larger grain size is seen after solidification.	It is a faster process and hence smaller (liner) grain size is seen after solidification.
critical size of the nucleus required is larger.	critical size of the nucleus requited is smaller