Viscosity of Al-Ni-Co-Nd(Sm) glass-forming melts at high temperatures.

Obtaining amorphous alloys with good mechanical and anticorrosion properties is an important problem of modern condensed matter physics. Since the preparation of amorphous alloys involves casting them from liquid state, information on the properties of the melts is needed. Viscosity is one of the most informative structure-sensitive property of melts. In this paper viscosity of some glass-forming Al-Ni-Co-Nd(Sm) melts with different ratio of transition metals was studied using damped oscillation method in a wide temperature range up to 1550 K. Activation energies of the viscous flow were calculated from the experimental data. The hysteresis of viscosity temperature dependences during heating and subsequent cooling was found. It can be associated with a melt transition to a more homogeneous state. The repeated heating and cooling of the melts without crystallization lead to Arrhenius type of viscosity temperature dependences.

Influence of rare earth metals on volumetric characteristics of Al-Ni-Co-R alloys in crystalline and liquid states.

Density of Al-Ni-Co-R (R = Nd, Sm, Gd, Tb, Yb) glass-forming alloys is studied experimentally by gamma-absorption method in a wide temperature range including crystalline and liquid states. Molar volumes and thermal expansion coefficients are calculated from the experimental data. It is shown that these melts remain strongly microheterogeneous systems at small overheatings above liquidus. Some regimes of melt heat treatment before quenching are discussed.