Metal flux synthesis—combining reactants in an excess of molten metal that acts as a solvent and in many cases as a reactant—has been found to be an excellent means of growing large crystals of intermetallic phases. Dissolution of the reactants in the flux renders them active at temperatures well below their melting point, permitting reactions to occur at much lower temperatures than are usually needed for traditional solid state synthesis. This makes the formation of novel metastable materials more likely.

Despite the increasing popularity of this technique, the ability to predict the nature of products remains elusive, but it is highly useful for exploratory synthesis. Certain trends in flux reactivity become evident from an overview of past research and current work on mixed fluxes (eutectic mixtures of metals used as a solvent). Reactions in calcium/zinc eutectic produce multinary phases containing both of these elements such as CaPdZn, Ca₆Pt₃Zn₅, and Ca₂AgZn. On the other hand, reactions in lanthanum/nickel eutectic often produce phases rich in La but containing no nickel, such as La₂₁Fe₈Bi₇C₁₂ and La₆Fe₉(Fe/Al)₄Bi. Possible explanations and avenues to control the structures of products by modification of reaction components and ratios will be discussed.