THERMOPHYSICAL PROPERTIES OF DOPED RARE-EARTH METAL ALLOY ZN55AL

Abstract

The paper presents the results of a study of the thermophysical properties of Zn55Al alloy doped with scandium, yttrium, cerium, praseodymium, neodymium and europium in a wide temperature range. It was established that in all studied samples anomalous cooling associated with a first-order phase transition is observed. It is assumed that the two observed cooling processes of the alloy are associated with radiative and convective heat transfer. It was revealed that the radiation process ends quickly and the sample is subsequently cooled only due to convective heat exchange with the environment. Using data on the temperature dependence of the heat capacity of aluminum and zinc, the temperature dependences of the heat capacity of the Zn55Al alloy and its heat transfer coefficient were calculated using the Neumann- Kopp rule . The results obtained show that the temperature dependence of the heat capacity is described by the polynomial С(Т)=a + b T + c T2 + d T3. It has been shown that the heat capacity of alloyed alloys is less than that of the original alloy and increases with increasing temperature, and changes differently with increasing concentration of the alloyed metal. For Zn55Al alloys alloyed with europium, cerium and neodymium, the heat capacity decreases with increasing concentration, and for alloys alloyed with praseodymium and scandium it increases. The phase transition process is observed in the Zn55Al alloy and becomes more pronounced upon alloying, which is explained by the process of monotectoid transformation α1→α2+β at a temperature of 529 K. It is shown that the results obtained are consistent with the zinc-aluminum phase diagram.