Heterogeneous Nucleation

Heterogeneous nucleation is metal solidification process that forms a new phase core adhered to impurities in the liquid phase or foreign surfaces, also called nonuniform nucleation, inhomogeneous nucleation, or non-spontaneous nucleation. Because such external factors as impurity particles or the inner wall of the mold will promote the formation of crystal nuclei, the new phase preferentially nucleates at the heterogeneous matrix in the parent phase. Adhering to these existing surfaces can reduce the nucleation interface energy, thereby reducing the nucleation resistance, so that nucleation can occur at a lower supercooling degree. Generally, the supercooling degree of metal solidification nucleation is not more than 20 °C, so the nucleation process of metal solidification is mostly heterogeneous nucleation. The critical nucleation radius of heterogeneous nucleation is the same as that of homogeneous nucleation, but its critical nucleation work is closely related to the contact angle...