Experimental study of the Cu-Ni-Y system at 700 °C using diffusion couples and key alloys

► Isothermal section at 700 °C of the Cu-Ni-Y system has been constructed. ► Diffusion couple technique has been used to understand the phase relations. ► Complete mutual solubility between CuY*-NiY and Cu4Y-Ni4Y have been determined. ► Maximum ternary solubility of the binary compounds has been determined.