The NbC-Re Polythermal Section in the Niobium—Rhenium—Carbon System
The structure of the NbC-Re polythermal section of the Nb-Re-C system has been investigated by the x-ray, metallographic, and chemical methods of analysis and by making microhardness and melting-point measurements. It was found that the NbC—Re system is of the eutectic type, with the eutectic point at 2225 ± 15°C, 70 at.% Re, and that the solubility of rhenium in NbC is small, being 1.5 at.% at 2000–2100°C. The (δ + β) field extends to 96–98 at.%Re. The lattice parameter of the δ -phase in the δ and (δ + β) fields as a function of its rhenium content decreases from 4.470 A (the value given in the literature) to 4.469 A at 2000–2100°C. The microhardness of the δ -phase is related to the solid solution of rhenium in NbC and that of the β-phase to the solid solution of carbon in rhenium.
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