Phase equilibrium in the system Y-Ni-In at 870 K

Abstract

Interaction of the components in Y ‑ Ni ‑ In system was investigated by X-ray powder methods and isothermal section of phase diagram was constructed at 870 K in full concentration range. The samples were synthesized in an arc-furnace on a water-cooled Cu-plate under an argon atmosphere and annealed in silica tubes at 870 K for one month. The phase analysis was performed by X-ray powder diffraction method. Twelve ternary compounds, namely YNi 9 In 2 (YNi 9 In 2 -type structure), Y 1-1 . 40 Ni 4 In 1-0 . 60 (MgCu 4 Sn-type structure), YNiIn 2 (MgCuAl 2 -type structure), Y 4 Ni 11 In 20 (U 4 Ni 11 Ga 20 -type structure), YNi 1 . 00-0 . 50 In 1 . 00-1 . 50 (ZrNiAl-type structure), Y 2 Ni 2 In (Mn 2 AlB 2 -type structure), Y 2 Ni 1 . 78 In (Mo 2 FeB 2 -type structure), Y 5 Ni 2 In 4 (Lu 5 Ni 2 In 4 -type structure), Y 11 Ni 4 In 9 (Nd 11 Pd 4 In 9 -type structure), Y 12 Ni 6 In (Sm 12 Ni 6 In-type structure), Y 13.84 Ni 3.19 In 2.97 (Lu 14 Co 3 In 3 -type structure), ~Y 3 Ni 0.05 In 0.95 (AuCu 3 -type structure) exist in the Y ‑ Ni ‑ In system at the temperature of annealing. Compound Y 3 Ni 2.26 In 3.74 exists at higher temperature. The substitution of Ni for In was observed for YNi 1.00-0.50 In 1.00-1.50 and In for Y in the case of Y 1-1,40 Ni 4 In 1-0,60 compound. Besides, yttrium can enter the structure of NiIn (CoSn-type) leading to formation of including-subtraction type solid solution, which is stable for 0 ‑ 8 at. % Y. The composition of this solid solution can be described by the formula Y 0-0 . 16 NiIn 1-0 . 93 . The inclusion of yttrium and indium atoms in position (2 e ) with the simultaneous exclusion of a small amount of indium atoms from position (1 a ) takes place in the homogeneity range of this solid solution. The character of component interaction in the ternary Y ‑ Ni ‑ In system is similar to other related ternary system R ‑ T ‑ In ( R – rare earth of the yttrium subgroup). The common feature of all these systems is the existence of large number isotypical ternary compounds, the formation of homogeneity range for compounds with ZrNiAl and including-subtraction type solid solutions based on the binary compound NiIn. Keywords: yttrium, indium, nickel, phase equilibria, ternary compound, crystal structure.