Free surface energy as a criterion for the sequence of intermetallic layer formation in reaction couples

We propose a new criterion for predicting the first growing phase and the phase growth sequence in a binary system in which several compounds are formed: the free surface energy of the components and compounds. The compound with the lowest free surface energy is the first to grow. The sequence of formation for layers of the other possible compounds is determined by the values of their fee surface energies. If compounds exist in the system with close surface energies, the compound with fewer atoms in the unit cell is more likely to form first. We propose using the S. I. Popel'-V V. Pavlov equation to calculate the free surface energy of hard intermetallics. We demonstrate the high predictive power of the proposed criterion.