Tungsten doping enhances the mechanical properties of FeCr2V-based medium entropy alloy revealed by experiments and calculations

The medium entropy alloys (MEAs) composed of high-melting-point, low-activation elements often demonstrate favorable mechanical properties and reduced activation required for nuclear applications. In this work, novel low activation MEAs of FeCrV and FeCrVW as potential nuclear structural materials have been developed. Thermodynamic calculation was used to guide the MEA design. The materials were fabricated using arc melting and their microstructure and mechanical properties were investigated. The results show that the developed MEAs are characterized by a dual-phase microstructure consisting of both body-centered-cubic (BCC) phases. The as-fabricated FeCrVW exhibits improved hardness (average nano-hardness 9.6 GPa) compared with FeCrV (7.4 GPa), owing to the enhanced solid solution strengthening (SSS) and precipitation strengthening (PS). Meanwhile, after doping with W, the compressive ultimate strength and yield strength of MEAs increased by about 15.7 % and 13.7 %, respectively. Being quantitatively consistent with the experimental results, the first-principles calculations based on the density functional theory (DFT) and the theoretical strengthening calculations confirmed that the W doping into FeCrV based MEA significantly enhanced the SSS and PS in the studied alloy. The results provide insights that are useful for future development and microstructural engineering of these novel MEAs.