THERMOPHYSICAL PROPERTIES OF Al–Ni–Co–R (R = Sm, Tb) ALLOYS IN CRYSTALLINE AND LIQUID STATES

Abstract

Experimental investigations of density and electrical resistivity of Al86Ni6Co2R6 (R = Sm, Tb) alloys were carried out in a wide temperature range, including crystalline and liquid states. Density was measured by gamma-penetrating method, and electrical resistance – by contactless method in rotating magnetic field. The solidus and liquidus temperatures were determined, the coefficients of volume expansion and the relative changes in density and resistivity during melting were calculated. The molar volumes of the alloys were calculated. It was found that the alloys are characterized by a wide two-phase zone where density and resistivity dependences show nonlinear behavior. At liquidus temperature an abrupt increase in density and a decrease in electrical resistivity were found. It has been established that terbium increases density of the alloys and reduces their resistivity more than samarium. In liquid phase at temperatures below T = 1300–1350 K density hysteresis was detected, and its absence on resistivity curves was shown. This may indicate the processes of large-scale inhomogeneities decay that do not cause changes in the electronic subsystem of the alloys but play a significant role in amorphization. The revealed features of the properties will make it possible to optimize the process of melts preparing before rapid quenching in order to obtain high-quality amorphous and nanocrystalline samples.