Simulations reveal atomic barriers in refractory alloy sintering

Molecular dynamics simulations have identified a kinetically constrained pathway for the solid-state sintering of the AlNbTiVZr refractory high-entropy alloy. The study examined how its five interacting elements affect atomic movement, melting and rearrangement as separate powder particles join and densify. Its results indicate that the alloy does not simply consolidate like a collection of elemental powders, offering an atomic-scale explanation for the processing challenges associated with this class of complex concentrated material.

The simulations revealed distinctive nanoscale thermal behavior, including size-dependent melting characteristics. The reported dihedral angles ranged from 40° to 120° throughout the sintering process, a result interpreted as evidence of stable interfacial configurations. This interface stability provides one part of the simulation-based picture of why joining the constituent elements into a dense refractory alloy can be difficult: the system retains constrained atomic arrangements while the particles undergo the changes required for consolidation.

The starting powder configuration proved to be a major factor. The researchers compared a pre-alloyed system with a mixture of separate elemental powders, and the two systems followed fundamentally different transformation pathways. In the pre-alloyed material, the constituent elements were already combined before sintering began. The mixed-powder system, by contrast, had to achieve chemical homogenization while the particles were simultaneously physically densifying. Those concurrent requirements introduced additional energy barriers and increased the complexity of the transformation.

By examining sintering at the scale of individual atoms, the study presents AlNbTiVZr as a simulation case for a broader challenge in refractory high-entropy alloys: multi-element interactions can make solid-state consolidation kinetically retarded. The evidence comes from large-scale molecular dynamics modeling of the alloy system, with the reported findings centered on nanoscale melting behavior, interfacial geometry and the distinct pathways available to pre-alloyed and mixed elemental powders. Within that modeled scope, the results connect powder configuration, chemical homogenization and physical densification to the difficulty of producing a consolidated refractory high-entropy alloy.

Subject of Research: Atomic-scale simulation of solid-state sintering in the AlNbTiVZr refractory high-entropy alloy

Article Title: Atomic-scale mechanisms of solid-state sintering in AlNbTiVZr high-entropy alloy

Article References: Gu, C., Wang, Y., & Zhao, J. (2026). Atomic-scale mechanisms of solid-state sintering in AlNbTiVZr high-entropy alloy. Journal of Materials Science, 61(41), 32180-32195. https://doi.org/10.1007/s10853-026-13682-z

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13682-z

Keywords: AlNbTiVZr, refractory high-entropy alloys, solid-state sintering, molecular dynamics, atomic mechanisms, chemical homogenization, physical densification, nanoscale melting, interfacial stability, materials processing, Atomic-scale, mechanisms