The Effect of short-range order on the viscosity and crystallization of Al-Mg melts

TL;DR

This study investigates how short-range atomic order influences the viscosity and crystallization behavior of Al-Mg melts across a wide composition range, revealing non-monotonic viscosity dependence and phase formation patterns.

Contribution

It provides new insights into the relationship between chemical short-range order and the physical properties of Al-Mg melts, using viscosimetry and thermal analysis methods.

Findings

Viscosity follows an exponential temperature dependence.

Viscosity's concentration dependence reflects changes in short-range order.

Certain compositions tend to non-equilibrium crystallization and quasi-eutectic formation.

Abstract

In this work, using the methods of viscosimetry and thermal analysis, the concentration changes in the values of the supercooling viscosity of Al-Mg melts with Mg content from 2.5 to 95 at.% are studied. It is shown that the temperature dependences of viscosity are well described by an exponential dependence. The concentration dependence of viscosity is not monotonous and reflects a change in the chemical short-range order in the liquid phase. The concentration dependence of supercooling of Al-Mg melts is determined by the type of solid phase formed during solidification, and also reflects the most significant changes in the chemical short-range order in the liquid phase at 20 and 80 at.% Mg. Al-Mg alloys in the concentration ranges: 0-10, 40-50 and 90-100 at.% Mg are prone to non-equilibrium crystallization, the formation of quasi-eutectics and solidification without intermediate intermetallic phases.