Microstructure and mechanical properties of the Nb37.7Mo14.5Ta12.6Ni28.16Cr7.04 multi-principal alloys fabricated by gas tungsten wire arc welding additive manufacturing

Abstract

In this study, we designed and developed a combined cable wire made of NbMoTaNiCr multi-principal alloys to meet the demand for high-temperature structural materials. On this basis, the gas tungsten arc welding (GTAW) wire arc additive manufacturing (WAAM) experiments of NbMoTaNiCr multi-principal alloys were conducted, and the microstructure and mechanical properties of the formed layer were analyzed and tested. The result showed that the formed NbMoTaNiCr multi-principal alloys layer at room temperature mainly exhibited a face-centered cubic (FCC) structure with a small amount of μ-phase. The microstructure exhibited the formation of fine and uniform dendrites, with certain dendrite segregation, accompanied by the changed elemental distribution. The high-temperature structural phases of the formed NbMoTaNiCr multi-principal alloys layer were BCC, FCC, B2, and μ-phase; the average hardness of the formed layer at room temperature was 911 HV, higher than that of all other systems with a solid-solution structure reported in the literature. At room temperature, the yield strength of the formed layer was 545.5 MPa, and the fracture strain was 9.5%. At 750 and 1100 °C, the fracture strains of the formed layer was 6.5 and 6.8%, respectively, while the corresponding yield strength of the formed layer was 597 and 490 MPa, much better than that of the conventional high-temperature alloy Inconel 718 (200 MPa) at 1000 °C.