The system Hf–Re–Si at 10000C

Abstract

The interaction of the components in the ternary system Hf–Re–Si was investigated by X-ray powder diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The isothermal section of the phase diagram at 10000C was constructed in the full concentration range. The limits of solubility of Si in the binary compounds Hf5Re24 and HfRe2 were found to be 11 and 16 at.%, respectively. The existence of three ternary compounds was confirmed and their crystal structures were refined: HfReSi2 (ZrCrSi2-type structure, space group Pbam, a=9.1271(3) Å, b=10.0356(4) Å, c=8.0708(3) Å), HfReSi (ZrNiAl-type structure, space group P-62m, a=6.9240(2) Å, c=3.3890(1) Å) and k-phase Hf9+xRe4–xSi (Hf9Mo4B-type structure, space group P63/mmc, a=8.5835(12) Å, c=8.7135(13) Å). The character of the interaction between the components in the Hf–Re–Si system and related ternary systems is briefly discussed.