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Divergence of temperature dependences of gamma-ray beam attenuation in the penetrated zone of Cu-Al melts at heating and subsequent cooling
Alexandre R. Kurochkin, Pjotr S. Popel, Alexandre V. Borisenko And Denis A. Yagodin
The authors made an attempt at measuring temperature dependencies of Cu-Al melts density by the absolute method of gamma-penetration at heating the samples after melting up to 1300–1400ºC and at their subsequent cooling. A divergence of gamma-ray beam attenuation curves corresponding to heating and cooling branches (hysteresis) has been found. This phenomenon is especially pronounced for alloys rich in aluminum, including CuAl (η-phase) and CuAl2 (θ-phase) compounds. The authors explain it by the irreversible breakdown of the metastable microheterogeneous state of melts inherited from the original crystal sample or appearing in the process of melting. This happens at heating up to homogenizing temperature which varies depending on the sample and which is close to the branching point of the curves.
Keywords: Cu-Al melts, density, gamma-method, metastable microheterogeneity