Electron diffraction study of cobalt-rich Hf-Co

Abstract Intermetallic compounds having compositions from HfCo 4 to HfCo 8 were investigated by transmission electron microscopy, selected-area electron diffraction, and energy-dispersive x-ray spectroscopy. A major crystalline phase, closely related to the orthorhombic Zr 2 Co 11 phase in structure, has been observed in the samples with the composition ranges from HfCo 6 to HfCo 8 . The phase, referred to as either Hf 2 Co 11 or HfCo 7 phase in the literature, is actually one common phase, having a broad composition range and referred to as μ -phase in the present paper. In addition to the μ -phase, we have found coexisted fcc-Co phase and a minor Hf 2 Co 7 phase. The Hf 6 Co 23 phase has been identified in the HfCo 4 and HfCo 5 samples. Tilt-series electron diffraction revealed that the μ -phase is a one-dimensional incommensurate structure, which can be described approximately as B-centered orthorhombic with a = 0.47 nm, b = 0.82 nm, and c = 3.86 nm.