Diffusion paths and phase equilibria in the MoNiCr system at 1425 K

Information about the structure of the MoNiCr phase diagram at 1425 K was obtained for the first time by a kinetic method in combination with the investigation of equilibrated alloys. The boundaries of the coexistence regions of the δ, ϱ and σ phases on the corresponding isothermal cross-section were established. The maximum chromium solubility in the δ phase of the Mo-Ni system was determined to be equal to about 12 at.% at this temperature. The satisfactory coincidence of the experimental data obtained by the diffusion couples technique and by analysing equilibrated alloys with the results of studying interdiffusion in the layered system molybdenum + nickel foil (50 μm) + chromium makes it possible to recommend the superposition of diffusion zones method for the rapid investigation of phase diagrams of the metallic system.