Phase equilibria in Ce–Cu–C ternary system at 400 °С and 600 °С

Abstract

Phase equilibria in Ce–Cu–C system at 600 °С and 400 °С have been studied using X-ray powder diffraction analysis and energy dispersive spectroscopy in the concentration ranges 0–40.0 at. and 40.0–100 at. % Ce respectively. The samples were prepared by arc melting under Ti-getter-purified argon atmosphere on a water cooled copper hearth using a nonconsumable tungsten electrode. The alloys were annealed in evacuated quartz glass ampoules at 600 °С and 400 °С for 6 and 12 weeksrespectively. The alloys are active on air. The crystal structure refinement of binary compounds was performed using WinCSD program package. Powder XRD data was obtained with a STOE STADI P (MoK α1 ) powder diffractometer (Debye-Scherrer geometry). Metallographic qualitative and quantitative compositional analyses of the polished samples were performed by EDX with REMMA-102-02 scanning electron microscope. Seven binary compounds – CeCu 6 , CeCu 5 , CeCu 4 , CeCu 2 , CeCu, α-CeC 2 , Ce 2 C 3 – have been confirmed to occur at 400 °С and 600 °С. They do not solute a third component C or Cu according to the X-ray structure and EDX analyses. No binary compounds occur in Cu–C system at 600 °С. No ternary compounds have been detected in the ternary system both at 400 °С and 600 °С. Probably, they may exist at higher temperatures and pressures. CeCu 4 binary compound has not been synthesized at 600 °С. Cerium and copper amount (19(2):81(2) at. %) has been measured by means of EDX technique. A more detailed investigation of CeCu 4 will be provided after the synthesis of well crystallized alloy. Cerium and copper amount was confirmed in the phases for other alloys by means of EDX technique. The results were in agreement with compositions of binary compounds. Keywords : ternary system, phase equilibria, rare earth carbides, crystal structure.