Tuning of mechanical properties of Tantalum-based metallic glasses

Abstract Metallic glasses (MGs) are materials characterized by high performance in terms of their mechanical properties such as excellent elastic behavior and high strength. These famous properties are directly linked to the amorphous structure which is the principal feature behind the absence of atomic order at long range. Nonetheless, MGs usually fail catastrophically by shear localization without showing any synonyms of important plastic deformation under mechanical solicitations and therefore are notoriously brittle, so the reinforcement of MG matrix to form MG-based composite materials is demanded. Molecular dynamics (MD) simulations are of great importance in designing such materials allowing atomic scale insights into the structural-mechanical properties relationship. In this work, we study the effect of adding Ta and W monocrystalline fibers in Ta-MG matrix using MD simulations with the embedded atom method (EAM) to describe the interatomic interactions. In addition, mechanical solicitations have been performed using a tensile test under a strain rate of 107 s−1, the evolutions of stress-strain curves have been compared between four samples (Ta-MG, nanoporous Ta-MG, monocrystalline Ta-reinforced Ta-MG and monocrystalline W-reinforced Ta-MG). Tensile tests have shown that plastic deformations are characterized by the localization of shear bands (SBs) in amorphous zones and the addition of Ta monocrystalline fibers increases the ductility and the toughness of the material and decreases its ultimate tensile stress (UTS); this ductility was found to be a result of the crystal growth inside the glassy matrix triggered by the crystal phase of the fiber. In contrast, the addition of W reinforces the MG matrix and increases the maximum strength and the toughness of the material, this improvement of the mechanical properties was explained by the presence of the heterogeneous interface which behaves as an obstacle to the propagation of SBs.