Pressure-induced irreversible volume collapse in a high-entropy alloy

作者：Raimundas Sereika, C.G. Knight, Kallol Chakrabarty, Andrew D. Pope, D. F. Smith, Yogesh K. Vohra · 发表于：Physical Review Materials · 年份：2025 · DOI：10.1103/zsmk-3vnt · 被引用次数：2 · 研究领域：High Entropy Alloys Studies、High-Temperature Coating Behaviors、Additive Manufacturing Materials and Processes

At ambient conditions, the high-entropy alloy superconductor R e 0.6 ( NbTiZrHf ) 0.4 exhibits exceptional mechanical properties among high-entropy alloys, with its hexagonal phase achieving nanoindentation hardness of 18.5 GPa. We report on a unique pressure-induced structural transformation from a hexagonal phase to a body-centered cubic (BCC) phase, revealed by synchrotron x-ray diffraction measurements up to 70 GPa. This first-order transition, accompanied by a 6.1% volume collapse, occurs at 44 GPa and results in a BCC structure with random site occupancy by the five constituent elements, which is remarkably retained upon decompression to ambient conditions. The transformation proceeds via a martensiticlike, diffusionless mechanism without elemental segregation, enabled by pressure-induced electronic redistribution and atomic-scale disorder. These findings demonstrate a rare case of metastable phase retention in a chemically complex alloy and offer new insights into structure-stability relationships under pressure.