| Abstract Scope |
Polymorphism and polymorphic transitions are attracting considerable interest due to their significant effects on phase stability, switchable properties, and the atomic rearrangement mechanism in materials. Here, by employing in situ high-pressure synchrotron x-ray diffraction in a diamond anvil cell, we reveal rich polymorphic transitions in the AlxCoCrFeNi high-entropy alloy (HEA) up to tens of GPa during compression and decompression. Much severe lattice distortion has developed under high pressure in the original body-centered cubic (bcc) phase compared to the initial face-centered cubic phase (fcc) phase. Lattice distortion affects the transition pressure, transition path, reversibility, stability at ambient conditions, etc. Our results demonstrate that the complex chemistry and the pressure-tuned lattice distortion may play a key role in introducing and stabilizing the rich polymorphs in the HEA, which could be a tuning knob to develop HEAs with novel structures and properties. |