Electronic structure and elasticity of the Ta-W solid solution

TL;DR

This study investigates how electronic structure influences the elastic properties and ductility of Ta-W alloys, revealing a correlation between Fermi level density of states and mechanical behavior across different transition metal systems.

Contribution

It provides new insights into the electronic origins of elastic constants and ductility in transition metal alloys, extending understanding beyond traditional elastic constant analysis.

Findings

Shear modulus slope change near equiatomic composition correlates with electronic structure shifts.

Electronic orbital characters near the Fermi level influence elastic behavior.

Similar electronic-elastic relationships are observed in other V and VI group alloys.

Abstract

The brittleness or ductility of metals has long been attributed to their elastic constants, with high Poisson ratio, or equivalently high Pugh ratio, favoring greater ductility. Growing evidence links ductility with their electronic structure. Consequently, it is desirable to understand how the electronic structure affects the elastic constants. Here, we examine the Ta-W binary alloy system, which evolves from ductile character at Ta-rich compositions to brittleness at high W. We show that a change in slope of the composition-dependent shear modulus near the equiatomic composition coincides with an abrupt change in the Fermi level density of states. We relate the behaviors of the elastic constants to the characters of occupied electronic orbitals close to the Fermi level. Finally, we consider additional alloy systems from groups V and VI and show that qualitatively similar behavior occurs more broadly.