МОДЕЛИРОВАНИЕ ЗАКОНОМЕРНОСТИ ИЗМЕНЕНИЯ ТЕМПЕРАТУРЫ И ЭНТАЛЬПИИ ПЛАВЛЕНИЯ ИНТЕРМЕТАЛЛИДОВ СИСТЕМ АЛЮМИНИЙ – ЛАНТАНИДЫ, БОГАТЫХ АЛЮМИНИЕМ

Abstract

The purpose of the article is determination and specification of thermochemical characteristics including melting temperature and enthalpy of lanthanides and intermetallic compounds of Al-Ln systems of Al2Ln, Al3Ln, α-Al11Ln3 and β-Al11Ln3 composition as well as system analysis and determination of variation regularity of thermochemical characteristics of objects depending on the nature of lanthanides. The system analysis of data is carried out using a semi-empirical method considering the features of the electronic structure of lanthanide ions. The methods of comparative calculation and differences are used to determine the thermochemical characteristics of intermetallic compounds of lanthanum, gadolinium and lutetium, which are not presented in the literature sources. The received values of the melting temperature of intermetallic compounds are used to calculate the values of their melting enthalpy by the known formula. Mathematical modeling of regularities is carried out in the Microsoft Excel software. The fullest data on melting temperature and enthalpy of lanthanides and intermetallic compounds of Al-Ln systems of Al2Ln, Al3Ln, α-Al11Ln3 and β-Al11Ln3 composition are received. The authors have found consistent variation patterns of thermochemical characteristics of lanthanides and intermetallic compounds of the named structures and developed their mathematical models also. Thus, it is established that the general feature of the determined variation regularities in the properties of lanthanides and intermetallic compounds of four studied structures is manifestation of a "tetrad effect" with clear classification by ceric and yttric subgroups. Characteristics of europium and ytterbium and their intermetallic compounds drop out of the general regularity. Mathematical modeling allowed to receive the equations that provide high reliability of determined regularity expression.