Structure and stability of Laves phases part II—structure type variations in binary and ternary systems

Abstract

In Part I, various models for the prediction of the occurrence and stability of Laves phases have been discussed. In the present Part II paper, an overview is given on the various types of manifestation of Laves phases in intermetallic alloy systems with emphasis on transition metal systems. Temperature- and composition-dependent as well as stress-induced phase transformations between the cubic C15 and the hexagonal C14 and C36 structural polytypes of Laves phases were observed in various binary and ternary systems. The phase fields of the different polytypes are generally separated by small two-phase fields. Some general rules for the occurrence of the different Laves phase polytypes are derived from a study of the results of experimental phase diagram investigations of various binary and ternary systems. The solubilities and site occupancies of ternary additions in the different Laves phase polytypes and the mutual miscibility of different binary Laves phases are discussed. The need for careful experimental investigations of phase equilibria is demonstrated. Existing models discussed in the preceding Part I paper are shown to fail to predict the structure and stability of the presented Laves phases in many cases.