Dr. Frank Stein
Max-Planck-Institut für Eisenforschung
Düsseldorf, Germany

Laves phases in binary and ternary systems: Stability, structure and mechanical properties

Abstract: Laves phases form the largest group of intermetallic phases and are often quoted as the classical example for atom-size-controlled compounds. They have attracted much attention as possible materials for high-temperature applications since long. Within the inter-institutional research initiative “The nature of Laves phases” of the Max Planck Society, Laves phases in a variety of binary and ternary transition metal-based systems have been investigated aiming at an improved understanding of the stability and structure of these phases. Laves phases may crystallize in three different, closely related structure variants, which are the cubic MgCu₂ type (C15), the hexagonal MgZn₂ type (C14), and the hexagonal MgNi₂ type (C36). Selected phase diagrams have been carefully re-investigated to study the co-existence of different Laves phase polytypes and the extension of their frequently very large homogeneity ranges. The composition dependence of the crystallographic parameters and the role of chemical disorder and site occupations are discussed showing the importance of intrinsic differences between the cubic and the hexagonal Laves phase polytypes. Finally, the dependence of the mechanical properties of single-phase Laves phase material on structure and composition will be presented revealing an unexpectedly strong effect of deviations from stoichiometry.

For more information contact STKS secretary: Hildegard.Wawrzik@rub.de

The seminar takes place on Tuesday, April 24, 10:00 a.m. in the ICAMS seminar room UHW 11/1102, Stiepeler Straße 129, 44801 Bochum.