SN-ZN SYSTEM - CORRELATION BETWEEN THERMODYNAMIC PROPERTIES, PHYSICAL-PROPERTIES, STRUCTURE AND PHASE-DIAGRAM

There is a good deal of ambiguity in the thermodynamic data for Sn-Zn alloys reported by various authors. Thermodynamic studies for this sys tem have shown that DELTAH > 0, and also a negative deviation of DELTA C(p) from the Neumann-Kopp rule. These facts indicate a transitional c haracter of the Sn-Zn alloys between systems with a miscibility gap an d those with a compound-forming tendency. However, the calculated stru ctural parameters of Bhatia-Thornton, S(cc)(0) and S(0)themodynamic, d o not exhibit any extrema. The isothermal relations of the viscosity a nd of the surface tension are similar, and decrease for Zn-rich alloys . The surface 'phase' is characterized by a pronounced tin enrichment by comparison with the bulk phase. In addition, the thermodynamic prop erties of the surface 'phase' indicate a negative deviation from ideal ity, while the bulk phase exhibits a positive deviation.