The temperature dependences (from the melting temperature to 1200 °C) of the kinematic viscosity of liquid aluminum and Al-Ni alloys with a nickel content of up to 1 at.% were obtained by the method of torsional vibrations. For all the liquid alloys studied, the temperature dependences of the viscosity obtained in the heating and cooling regimes coincide. Approximation of temperature dependences by the Arrhenius equation is carried out. For the liquid aluminum and the melts with a nickel content below 0.5 % inclusive, we discovered a deviation of the temperature dependences of the viscosity from the Arrhenius dependence. We might divide polytherms of the viscosity of these melts into two temperature intervals; in each interval, the dependence is described by the Arrhenius dependence. The fracture temperature does not depend on the nickel content and is close to 910 °C. With an increase in the nickel content in the melt, the fracture effect decreases. The polytherm of the viscosity of a melt containing 1.0 % nickel is described by the Arrhenius equation throughout the temperature range studied. The deviation of the melt viscosity polytherms from the Arrhenius equation is probably caused by a structural transformation in the liquid aluminum. We explain the decrease of the deviation of the temperature dependence of the viscosity from the Arrhenius equation with increasing nickel content by a change in the structure of the melt upon alloying. It is assumed that clusters consisting of Ni atom and surrounding Al atoms (Al(Ni) cluster) are formed in the melt even at low nickel contents. An increase of the nickel content leads to growth of number of Al(Ni) clusters and a decrease of the volume fraction of the melt with a short ordering characteristic for liquid aluminum. Concentration dependences of viscosity and activation energy of viscous flow are constructed. An increase of the nickel content in the melt leads to growth of values of the viscosity and activation energy of the viscous flow. The most intensive growth of values of the viscosity is observed with an increase in the nickel content to 0.15 %.
|Título traducido de la contribución||Viscosity of Al-Ni melts with small nickel content|
|Número de páginas||10|
|Publicación||Химическая физика и мезоскопия|
|Estado||Published - 2017|
Level of Research Output
- VAK List