Bulk and surface properties of Al–Co and Co–Ni liquid alloys

The energetics of mixing in Al–Co and Co–Ni liquid alloys has been analysed through the study of surface properties (surface tension and surface composition), dynamic properties (chemical diffusion and viscosity) and microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter) in the frame of statistical mechanical theory in conjunction with quasi-lattice theory (QLT). The phase diagram of the Al–Co system exhibits the existence of different intermetallic compounds in the solid state, while a lens type phase diagram of the Co–Ni system indicates nearly ideal behaviour in both the solid and liquid phases. Since the structure of a liquid alloy is in some respects similar to that of a crystal, the complex formation phenomenon in Al–Co liquid alloys has been analysed by a quasi-lattice structural model for the chemical complexes. The energetics and structural arrangement in Co–Ni melts have been studied by the quasi-chemical approximation (QCA) for the regular solution model.