C. J. Ruestes | Searcharxiv

arXiv2026

Mechanical Scaling Laws and Deformation Behavior of Nanoporous Tantalum Microparticles

The mechanical scaling laws of dealloyed nanoporous metals depart from classical Gibson-Ashby predictions for open-cell foams due to a decreased connectivity in their solid network. However, these scaling relations have been established almost exclusively on nanoporous gold produced by electrochemical dealloying, and it is an outstanding question whether the relations apply to nanoporous networks fabricated by other dealloying methods. Here, we investigate the mechanical response of single-crystalline nanoporous tantalum (np-Ta) produced by liquid metal dealloying (LMD) a TiTa alloy in molten CuBi. Nanoindentation of individual microparticles yields an elastic modulus of 10-30 GPa and a hardness of 0.3-1.1 GPa, both scaling with the solid volume fraction in agreement with Gibson-Ashby predictions. This stiffness-density response of np-Ta departs from previous reports on nanoporous gold and is attributed to enhanced ligament connectivity enabled by the thermodynamics of the CuBi metal bath. Molecular dynamics simulations reveal dislocation-dominated plasticity during indentation of np-Ta, consistent with scanning electron microscopy observations of limited densification beneath the indents, ruling out unusual deformation mechanisms as an origin of the observed scaling. These findings identify solvent chemistry in LMD as a tunable lever for ligament connectivity, and thus for the mechanical response of nanoporous metals.

cond-mat.mtrl-sci↗

arXiv2024

Topological changes and deformation mechanisms of nanoporous Ta under compression

While the mechanical behavior of noble nanoporous metals has been the subject of numerous studies, less is known about their recently developed refractory-based counterparts. Here we report on the mechanical properties, deformation mechanisms and topological changes of nanoporous tantalum, a prototypical refractory metal, by means of atomistic simulations of compression tests. An open-source multi-cpu and gpu-capable software is presented and used for the generation of computational samples. The stress strain curves show a non-linear elastic response, with early yielding. The plastic regime is first characterized by a linear hardening followed by an exponential hardening at large strains, associated with a high degree of densification. Plasticity is dominated by dislocation activity, with twinning and vacancy formation appearing as complementary deformation mechanisms. In order to study the mechanical response from a topological perspective, we track the evolution of the genus throughout the tests, finding direct correlations with each regime of the stress strain curves. The results are in agreement with previous studies of plasticity in nanoporous metals and highlight the importance of using topological metrics, for gaining insights into complex aspects of the deformation of nanoporous metals.

cond-mat.mtrl-sci↗