Crystal structure of the binder phase in a model HfC-TiC-Ni material

The crystal structure of the binder phase in a model HfC-TiC-Ni sample produced by hot pressing is investigated. The nature of the binder depends on the amount of Hf and Ti that remains in solution with Ni after cooling. Four different crystal structures are identified by analysis of electron diffraction patterns obtained using transmission electron microscopy techniques and the composition of the phases determined by energy dispersive X-ray spectrometry. Three of the phases are cubic; Ni, Ni3(Ti,Hf) and Ni23(Ti,Hf)6 with lattice parameters of 3.52 ± 0.05, 3.52 ± 0.03 and 10.70 ± 0.40 Ǻ, respectively. The hexagonal phase is an intermetallic Ni3Ti phase, with lattice parameters of a = b = 5.00 ± 0.20 Ǻ and c = 8.16 ± 0.20 Ǻ. The crystal structures are confirmed by simulations of the electron diffraction patterns using JEMS software.