Study on the extreme thermodynamic conditions for the synthesis of CoCrFeNiMox (x = 0–0.3) alloy

Abstract

Multicomponent alloys prepared using different experimental methods under atmospheric pressure have been widely studied. However, research on multicomponent alloys involving methods using high pressures and high temperatures is still in its infancy. In the high-pressure CoCrFeNiMox alloy, the combination of each element atom and the change in the sample crystal structure indicate a relationship between the evolution mechanism of the multi-element alloy microstructure and high pressure. We observe that molybdenum (Mo) atoms enter the medium-entropy alloy (MEA) lattice near its theoretical recrystallization temperature to form a high-entropy alloy (HEA). The diffusion of Mo atoms requires the energy provided by the temperature to overcome the low-entropy effect under high pressure, Mo atom reacts with MEA near its recrystallization temperature to form HEA means the formation of HEA under high pressure follows the specific steps. High pressure inhibits grain growth and generates numerous dislocations in the crystal, thereby preparing the high-pressure CoCrFeNiMox alloy with a high hardness of 3.7 ± 0.12 GPa, which is harder than the CoCrFeNiMox alloy prepared under atmospheric pressure. Additionally, the generalized high-pressure HEA constant is introduced, which is 1 ≥ P ≥ 0.17, proving that high-pressure promotes the synthesis of HEAs. This constant provides a new method for studying the thermodynamic behavior of HEAs under extreme conditions.