Abstract: Refractory high-entropy alloys (RHEA) exhibit outstanding strength at room temperature, but their practical applications are often limited due to inherent brittleness. Herein, we design and fabricate dual-phase Ni_xMoVW RHEAs (x = 0.25, 0.5, 0.75, 1.0) with tunable body-centered cubic (BCC)/face-centered cubic (FCC) phase fractions via laser melting deposition. Increasing the Ni content promotes the formation of the FCC phase, enhancing liquid backfilling during solidification and thereby mitigating cracking. The rapid solidification inherent to the additive manufacturing process effectively suppresses elemental segregation and promotes microstructural refinement. Compressive tests show that the Ni_1.0MoVW alloy achieves an excellent strength-ductility balance, with a yield strength of 1635.5 MPa, an ultimate strength of 2294.7 MPa, and a plastic strain over 14.74 % at room temperature. First-principles calculations attribute this superior mechanical performance to the intrinsic stability of both BCC and FCC phases and the strong interfacial bonding at their boundary. This study presents a viable strategy for developing high-performance, crack-resistant RHEAs through compositional tuning and additive manufacturing. The findings provide valuable insights into interfacial strengthening mechanisms in heterogeneous metallic systems.

Key words: First-principles calculation, Laser melting deposition, Mechanical properties, Refractory high-entropy alloy, Strengthening mechanism