Interaction between the components in the Zr-V-Sb system at 870 K

Interaction between the components in the Zr–V–Sb ternary system was studied at 870 K over the whole concentration range using methods of X-ray diffractometry and energy dispersive X-ray spectroscopy. The alloys for investigation were prepared by arc melting the stoichiometric amounts of the constituent elements under high purity Ti-gettered argon atmosphere on a water-cooled copper hearth. The 3-5 wt. % excess of Sb was required to compensate the evaporative losses during arc-melting. The arc-melted ingots were then annealed at 870 K in evacuated quartz glass tubes for 720 hours and subsequently cold water quenched. The synthesized and annealed samples are stable in atmospheric conditions. For the characterization of the annealed samples X-ray powder diffraction on DRON-2.0m diffractometer with Fe K α radiation was performed. The chemical and phase compositions of the produced samples were examined by Scanning Electron Microscopy (SEM) using Tescan Vega 3 LMU electron microscope. At the temperature of investigation 870 K phase relations in Zr-V-Sb system are characterized by existence of two ternary compounds: Zr 5 V 0 . 5 Sb 2 . 5 (Nb 5 Sn 2 Si structure type, space group I 4/ mcm , a = 1.11128(1), c = 0.55847(1) nm) and Zr 2 V 6 Sb 9 (Zr 2 V 6 Sb 9 structure type, space group P 4/ nmm , a = 0.9781(3), c = 0.7193(3) nm). For Zr 5 V 0 . 5 Sb 2 . 5 antimonide the crystal structure was refined by X-ray powder diffraction method (STOE STADI P diffractometer). Solubility of V in ZrSb compound (ZrSb structure type) extends up to 7 at. % ( а = 0.3795(1), b = 1.0373(2), c = 1.3989(5) nm for ZrSb binary, а = 0.3762(3), b = 1.0358(5), c = 1.3883(7) nm for Zr 50 V 7 Sb 43 sample). Solubility of the third component in other binary compounds is less than 1.5 at. %. Analysis of the Zr–V–Sb system and studied early Zr–M–Sb (M–Cr, Mn, Fe, Co, Ni, Cu) showed that the ternary compounds with Nb 5 Sn 2 Si structure type appear in all these systems. The reduced number of the ternary phases in the Zr–V–Sb system comparing with related Zr-M-Sb (M = Fe, Co, Ni, Cu) systems shows an important influence of d -metal on the formation and structure of intermediate ternary phases. Keywords : intermetallics, ternary system, crystal structure, phase equilibria.