Ural Federal University, Ekaterinburg, Russia:
V. V. Baraz, Professor of a Chair of Metal Science, e-mail: vrbaras@mail.ru
S. S. Gerasimov, Head of Laboratory of a Chair of Art Materials Processing Technology
A. O. Sedelnikova, Student of a Chair of Metal Science
I. A. Gruzdeva, Head of a Chair of Art Materials Processing Technology

The article presents a research on properties of Cu – Ni – Zn ternary system alloys. Nickel silver alloys are applied in instrument making, shipbuilding and for production of medical instruments. In addition, nickel silvers are widely used in production of cutlery and jewels. It is known that the addition of aluminum and tin to Cu – Ni – Zn ternary systems improves the casting mold’s fillability. This is very important if we wish to obtain a thin and sophisticated cast billet. In this respect, the influence of Sn and Al doping was researched by the method of experiment planning, whilst the influence of crystallization temperature on the structure as well as strength and casting properties of a Cu – 15Ni – 20Zn nickel silver, which contains 14.1% of Ni and 20.2% of Zn as its main components, was also studied. A research was conducted on a cast billet that was obtained through a process of casting wax. The melting and filling were conducted in the Induthermmuv-700 induction vacuum casting unit. The concentration of the components was determined with the Spectromidex X-ray fluorescence analyzer with an accuracy of 0.1% (wt.). A metallographic study was carried out with the automated scanning microscope Epiquant. Surface topography of the bars was measured with the optical profiler WykoNT 1100. Aluminum doping (0.4%) has a positive influence on the casting mold’s fillability and improves the surface significantly. Doping of tin up to 4% helps to increase the yield stress 0.2 (to 65–70%) with the ductility staying at a satisfactory level. The mold temperature at the time of casting does not have a significant impact on the microhardness. Its lowering from 550 to 450 ^оС leads to a relative reduction of grain sizes and an insignificant increase of yield stress — 0.2. The surface condition was also measured. The addition of aluminum and tin reduces the surface roughness significantly.

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