A strategy for optimizing microstructure to simultaneously improve the strength and plasticity of W-Ni-Fe alloy

The conventional sintered W-Ni-Fe alloy encounters challenges in achieving both high strength and plasticity simultaneously, primarily due to its inadequate organizational compatibility. To address this issue, we developed a novel approach combining in situ freeze-drying and straightforward liquid-phase sintering techniques to effectively control the microstructure of 93W-4.9Ni-2.1Fe alloys. The corresponding W-Ni-Fe alloy in this work simultaneously takes into account ultrafine W grains (28.3 µm), low W-W connectivity (CW-W = 0.31), and suitable γ phase volume fraction (20.2%), which is currently difficult for traditional W-Ni-Fe alloys to achieve. The minute dimensions of nanopowder play a crucial role in inhibiting Ostwald ripening and facilitating W grain refinement. Additionally, the extensive surface area of nanopowder enhances capillary penetration, leading to effective homogenization of high γ phase volume. As a result, the freeze-dried W-Ni-Fe alloy simultaneously achieves high strength (1010 MPa) and high plasticity (31%), which provides a new insight for the further development of W-Ni-Fe alloy industries.