Alpha factor

The α-factor is a dimensionless quantity used to predict the solid–liquid interface type of a material during solidification. It was introduced by physicist Kenneth A. Jackson in 1958. In his model, crystal growth with larger values of α is smooth, whereas crystals growing at smaller α have rough surfaces.

Method

According to John E. Gruzleski in his book Microstructure Development During Metalcasting :
where is the latent heat of fusion; is the Boltzmann constant; is the freezing temperature at equilibrium; is the number of nearest neighbours an atom has in the interface plane; and is the number of nearest neighbours in the bulk solid.
As, where is the molar entropy of fusion of the material,
According to Martin Glicksman in his book Principles of Solidification: An Introduction to Modern Casting and Crystal Growth Concepts :
where is the universal gas constant. is similar to previous, always < 1.