Pressure-induced ordering phase transition in high-entropy alloy

The order-disorder transition has long been viewed as an important key to study materials structures and properties. Especially, pressure-induced ordering attracted the intense research interest in the recent years. In the present work, the pressure-induced ordering phase transition (disordered-fcc to ordered-fcc structures) in a CoCrCuFeNiPr high-entropy alloy (HEA) was found by employing the in situ high-pressure energy-dispersive X-ray diffraction (EDXRD) technique. It is interesting to note that there exists a pressure-induced fast ordering transition at the pressure ranging from 7.8 GPa to 16.0 GPa, followed by a slow transition with the pressure increase up to 106.4 GPa. We suggest that this phenomenon is caused by the presence of some short-range-order (SRO) local structures in the CoCrCuFeNiPr HEA. These SRO structures can be regarded as embryos, which will develop into the ordered phase with increasing the pressure in the prototype materials. This pressure-induced ordering may provides a new technique for tuning structures and properties of HEAs.