Дослідження взаємодії компонентів у системі Sm-Li-Co-Si за температури 400С

Abstract

The interaction of the components in the Sm-Li-Co-Si system in the SmSi-LiSi-CoSi-Si region was investigated by X-ray phase, local X-ray spectral analyses and microstructural analysis at 400ºC.

The alloys were prepared by arc melting of stoichiometric amounts of the constituent elements in an arc furnace under argon atmosphere. The alloys were annealed in evacuated silica tubes at 400ºС for 480 hours and quenched in cold water. Flame photometer Flapho-4 was used for the experimental determination of lithium amount. To confirm the phase composition of some system samples energydispersive X-ray spectroscopy method (EDX) was used (scanning electron microscope REMMA-102- 02). The calculations and indexing of diffraction powder pattern (STOE STADI P diffractometer, Cu Kα1-radiation) have been conducted using LATCON and POWDER CELL-2.3 software. Calculations to refine the structure of samples have been carried out by with WinCSD and FullProf 98 programs. It was discovered for the first time, that in the investigated system limited solid solutions of SmLi1-хCoxSi2 (structural type CaLiSi2, Pearson symbol oP16, space group Pnma, 0 ≤ x ≤ 0,31, a = 0,7711(3)-0,7699 (3); b = 0,3862(2)-0,3848(3); с = 1,0481(7)-1,0467(8) nm) and SmLixCo1-xSi2 (structural type СеNiSi2, Pearson symbol oS16, space group група Cmcm, 0 ≤ x ≤ 0,27, a = 0,4087(1)- 0,4102(3); b = 1,6319(2)-1,6335 (8); с = 0,4007(1)-0,4025(2) nm) were formed on the cross-section between SmLiSi2 and SmСоSi2 compounds. The boundary lines of solid solutions are set according to the graphs of unit cell volume change. Existence of SmSi2-x, SmSi, CoSi2, CoSi compounds, Sm–Si and Co–Si binary systems, and four ternary phases of Sm–Li–Si та Sm–Со–Si systems has been confirmed. Quaternary compounds in the investigated areas were not observed. Keywords: Samarium; Lithium; Cobalt; Silicon; phase equilibria; synthesis; crystal structure; solid solution.