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.