Irregular Homogeneity Domains in Ternary Intermetallic Systems

• Main Authors: Jean-Marc Joubert, Mohamed Andasmas, Jean-Claude Crivello
• Format: Article
• Language: English
• Published: MDPI AG 2015-12-01
• Series: Applied Sciences
• Subjects: phase diagrams; DFT; Rietveld; site occupancies; homogeneity domains
• Online Access: http://www.mdpi.com/2076-3417/5/4/1570

Ternary intermetallic A–B–C systems sometimes have unexpected behaviors. The present paper examines situations in which there is a tendency to simultaneously form the compounds ABx, ACx and BCx with the same crystal structure. This causes irregular shapes of the phase homogeneity domains and, from a structural point of view, a complete reversal of site occupancies for the B atom when crossing the homogeneity domain. This work reviews previous studies done in the systems Fe–Nb–Zr, Hf–Mo–Re, Hf–Re–W, Mo–Re–Zr, Re–W–Zr, Cr–Mn–Si, Cr–Mo–Re, and Mo–Ni–Re, and involving the topologically close-packed Laves, χ and σ phases. These systems have been studied using ternary isothermal section determination, DFT calculations, site occupancy measurement using joint X-ray, and neutron diffraction Rietveld refinement. Conclusions are drawn concerning this phenomenon. The paper also reports new experimental or calculated data on Co–Cr–Re and Fe–Nb–Zr systems.