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With low-cost and high-efficiency advantages, wire arc additive manufacturing (WAAM) has become a promising method for preparing high-entropy alloys (HEAs). This study prepared CoCrFeNiMo 0.2 HEA samples using cold metal transfer technology. By changing the deposition parameters, different heat inputs were realized. The forming quality, microstructure, and mechanical properties of the as-deposited CoCrFeNiMo 0.2 HEA samples with different heat inputs were explored by macroscopic observation, optical microscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, electron backscatter diffraction, microhardness and tensile test at room temperature. Results show that the alloy prepared by WAAM had a typical columnar crystal composition in deposition direction and a strong {100}〈001〉 cubic texture. With the increased heat input, the forming of the sample worsened, and an obvious step effect appeared, increasing the fine grain region between the sample layers. Due to the heat accumulation and poor heat dissipation, the phase with less Mo grew, deteriorating its mechanical properties. The growth direction of columnar crystals in the sample was consistent with the vertical tensile direction, improving the sample's tensile properties perpendicular to the deposition direction. • Wire arc additive manufacturing (WAAM) of CoCrFeNiMo 0.2 high-entropy alloys. • WAAM can produce high-entropy alloys with lower cost and high efficiency. • The effects of heat input on the forming quality of HEAs was investigated. • The microstructure and mechanical properties of the CoCrFeNiMo 0.2 HEAs were investigated. [ABSTRACT FROM AUTHOR]

Powder plasma arc additive manufacturing (PPA-AM) is a promising method for the preparation of high-entropy alloys (HEAs), and has the advantages of low cost, high efficiency, and high quality. In this study, the CoCrFeNiW x (x = 0, 0.2, 0.5, 0.7, and 1.0) HEAs were successfully prepared via the PPA-AM technique. Microstructure and mechanical properties of alloys with different W content were investigated. The results showed that the microstructure changed from a single FCC phase (x = 0) to the dual-phase FCC + µ (x = 0.2 and 0.5), and then to a three-phase combination of FCC + µ + BCC (x = 0.7 and 1.0) with the addition of W. The volume fraction of the µ phase and BCC phase increases with the increase in W content, while the size of FCC columnar grain is significantly reduced. The solid-solution strengthening of the FCC phase and the second phase strengthening were mainly responsible for the increase in the microhardness (136–413 HV) and yield strength (187–567 MPa) while the brittleness of the μ phase contributes to the expansion of the crack, which leads to a decrease in the ductility (50.8% to 0.3%). These results can provide a systematic understanding of the phase transformation of PPA-AM HEAs with different W content and its effects on the mechanical properties. • Powder plasma arc additive manufacturing (PPA-AM) of CoCrFeNiWx high-entropy alloys. • PPA-AM can produce high-entropy alloys with lower cost and high efficiency. • The microstructure and mechanical properties of the CoCrFeNiWx HEAs were investigated. • W element can promote the phase transformation from FCC phase to µ and BCC phase. • The strength of the HEAs was significantly improved with addition of W. [ABSTRACT FROM AUTHOR]