Determination of isothermal sections of Ni-Cr-Nb ternary system
(School of Materials Science and Engineering, Central South University, Changsha 410083, China)
Abstract: The isothermal sections of Ni-Cr-Nb ternary system at 1 323 K and 1 423 K were determined by means of diffusion triple and energy spectrum analysis (ESA). By analyzing the diffusion layers in the diffusion couples, the compounds forming in this system were identified. There are three similar compounds found at these two temperatures: Ni3Nb, NiNb and NbCr2-R, and four similar three-phase regions are found: (Ni)+(Cr)+Ni3Nb, Ni3Nb+NbCr2-R+NiNb, NbCr2-R+(Cr)+Ni3Nb, NbCr2-R+NiNb+(Nb). The results show that no phase transformation happens between these tow temperatures. But the solid solubilities of the binary compounds at 1 423 K become bigger than those at 1 323 K, especially the solid solubility of NbCr2-R. No ternary compound is observed.
Key words: Ni-Cr-Nb ternary system; diffusion triple; isothermal section