ReCALL: Electrical Resistivity of Concentrated Alloys

Electrical resistivity is one of the oldest and well-known characteristics of solid materials. For instance, it separates metals from insulators: For metals, the electrical resistivity is low and it increases with temperature, while insulators have the large resistivity which goes down with temperature. However, many technologically important metallic alloys with relatively high resistivity seem to violate this simple distinction. Specifically, their electrical resistivity does not behave like the one in normal metals, and can even decrease with temperature, as if the material was insulating. The origin of this behavior is not yet fully understood. In this project, we propose to use a unique combination of methods based on the ab initio approach to study peculiar electrical properties of highly resistive alloys, with the goal of unraveling the relation between the local atomic structure and the temperature evolution of the resistivity. Numerous theories have been put forward to explain the origin of the negative temperature dependence of the resistivity in metallic alloys. However, the main difficulty of these theories is that they all rely on simplified models, providing conflicting qualitative explanations of the phenomenon. Therefore, to distinguish between plausible alternative mechanisms, a quantitative comparison to experimental data is needed. In our approach, we will study the temperature-dependent resistivity using ab initio simulations of metallic alloys in all their complexity. To achieve this, we will combine a method that has successfully been applied to accurately describe complex multicomponent alloys with a formalism for calculating electrical resistivity that has recently been extended to correctly take into account the temperature dependence. Two major outcomes from the project are expected. On the one hand, we will use our novel methodology to identify the mechanism of the unusual resistivity behavior in disordered alloys. On the other hand, the sensitivity of the electrical resistivity to the atomic structure of materials makes it an important tool for monitoring the structure evolution of alloys during their production. The application of this characterization technique to many technologically important alloys, such as, e.g., austenitic steels, high-entropy alloys, or bulk metallic glasses, is not possible due to the poorly understood peculiar behavior of their resistivity. Our novel methodology will enable one to interpret experimentally obtained resistivity data, giving access to important local atomic properties, such as atomic short-range order or random displacements, which are very difficult to measure in complex multicomponent alloys using conventional spectroscopic methods.

No additional funding sources recorded.