X-ray investigation of the Y–Zr–Ni system at 870 K

The isothermal section of the Y–Zr–Ni phase diagram at 870 K has been investigated by means of X-ray and microstructure analyses. One ternary compound YxZr1−xNi2 (0.12 ≤ x ≤ 0.20) occurs in the system. The crystal structure of Y0.12Zr0.88Ni2 has been investigated by single crystal X-ray diffraction: MgCu2 type structure, space group Fd-3m, a = 6.937(1) Å, Z = 8, R1 = 0.037 for 48 independent reflections Io > 2σ(Io)). Isotypic compounds with heavy rare earths RxZr1−xNi2 (x ∼ 0.12) (R = Gd–Lu) have been synthesized. The crystal structure of the binary compound ZrNi5 has been refined for the first time from the single crystal X-ray diffraction data: AuBe5 type structure, space group F-43m, a = 6.687(1) Å, Z = 4, R1 = 0.035 (wR2 = 0.036) for 63 reflections with Io > 2σ(Io). A morphotropic row of binary Laves phases Y0.97Ni2 (TmNi2-type structure, or as can be denoted “MgCu2”) towards ternary YxZr1−xNi2 (MgCu2 type structure) has been discovered.