Abstract
High-temperature resistant high-entropy alloys (HEAs) have attracted extensive attention due to their excellent thermodynamic stability and mechanical properties, especially at high temperatures. However, a highly effective method for large-size HEAs is still desirable but challengeable. This research reported a facile yet effective strategy for MoNbTaWTi HEAs via in-situ wire arc additive manufacturing (WAAM). The wire was MoNbTaWTi cable-type welding wire (CTWW) consisting of one center wire and seven twisted peripheral wires. Then, additive manufacturing of MoNbTaWTi high entropy alloys (HEAs) was accomplished, and various analytical techniques studied the microstructures and mechanical properties of the overlaying formed layers. X-ray diffraction showed the overlaying formed layers to contain a single disordered BCC solid solution phase with high-temperature structural stability. In addition, the single-phase BCC structure was maintained from 0 to 1400 °C. The bottom of the overlaying formed layers was made of columnar cellular structure, and the upper part resembled “cauliflower-like” fine dendrite and equiaxed crystal structure. The hardness of the overlaying formed layers averaged 533 HV0.2 at room temperature. At 1000 °C, the hardness was around 110 HV1, close to the value of Inconel 718 alloy (125 HV1). The compressive strength of the overlaying formed alloy layers displayed no sensitivity towards change in temperature from 500 to 1000 °C. As the temperature rose from 500 to 1000 °C, the compressive strength changed from 629 to 602 MPa, equivalent to only a 27 MPa decrease. The latter was much higher than the strength of Inconel 718 alloy at the same temperature (200 MPa).
Highlights
As a novel type of alloy including at least five principal elements, high entropy alloys (HEAs) have attracted extensive attention in science or industry since Prof
It could be concluded that surfacing formed MoNbTaWTi alloy fitted well with the above mixing principle, confirming the disordered solid solution phase of the formed layer
Additive manufacturing of MoNbTaWTi as high-temperature resistant HEA with a nominal composition of Mo30.7Nb13.4Ta13.4W15.2Ti27.3 was accomplished by arc surfacing technology
Summary
As a novel type of alloy including at least five principal elements, high entropy alloys (HEAs) have attracted extensive attention in science or industry since Prof. The high entropy thermodynamics, slow diffusion dynamics, lattice structural distortion, and cocktail performance [3]. It could form simple face-centered cubic (FCC) or body-centered cubic (BCC) solid solutions and nanoscale precipitates, leading to better properties in terms of high strength, elevated hardness, excellent thermal stability, good corrosion, and wear resistance. Su et al used the vacuum arc melting method and prepared high melting point alloys with equal molar ratios, such as TiZrHfVNb and TiZrHfVTa, TiZrHfNbMo, and TiZrVHfMo. The study of microstructures and properties of these alloys revealed as-cast alloys with phases of BCC, HCP, or BCC+ HCP solid solution. Given the insufficient strength of HfNbTaTiZr alloy at high temperature, Chien et al [23] designed and successfully synthesized HfMoTaTiZr and HfMoNbTaTiZr alloys with BCC single-phase structure. Many other researchers, such as Jayaraj [9], SaadSheik [26], Zhang Yong [27], Tong [28], etc., have developed lots of studies on high-temperature resistant HEAs
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