SAED and HREM Studies of Zr2Co11 Intermetallic Compound

Rare-earth-free permanent-magnets have gained immense focus in the view point of mitigating the critical-material aspects of rare-earth elements. The intermetallic compound Zr2Co11 is a promising candidate. Polymorphism exists in the Zr2Co11 compound; a high-temperature phase has a rhombohedral structure and a low temperature phase has an orthorhombic structure [1,2]. Both of the two phases in relative small grain sizes have been observed often in the same rapidly quenched samples. In this case, selected-area electron diffraction (SAED) and high-resolution electron microscopy (HREM) are the suitable experimental techniques to study the crystalline structures. Theoretical calculations predict that the lowest-energy structures near Zr2Co11 composition share a common structural motif [3]. The combination of theoretical and experimental results allows correct structural models of the two Zr2Co11 phases to be constructed.