Optimization of microstructure and mechanical properties of microwave-sintered V/Ta/Re-doped tungsten heavy alloys

Abstract The inherent brittleness and high-temperature recrystallization tendency of tungsten heavy alloys (WHAs) make balancing high strength and ductility under harsh conditions a major challenge. This study introduces V, Ta, and Re as strengthening elements into W-Ni-Fe-Co alloys by powder metallurgy, producing five alloy compositions (in weight fraction): the baseline sample S1 (W-2.46Ni-1.05Fe-0.7Co), single-doped samples S2 (1V), S3 (2Re), S4 (4Ta), and multi-doped sample S5 (1V-2Re-4Ta). The results show that S1 has the highest density of 98.6 ± 0.61 %; S3 has a peak hardness of 443.27 ± 13.33 HV; and S5 exhibits the best tensile strength and elongation, at 816.35 MPa and 8.92 %, respectively. These performance improvements are attributed to specific strengthening mechanisms: V enhances hardness and ductility through solid solution strengthening in the tungsten lattice and induces lattice distortion; Re promotes grain refinement and the formation of ReW phases, mainly enhancing hardness through grain boundary pinning; and Ta contributes to strength improvement by enriching and achieving second phase strengthening. In S5, the synergistic effect of multi-element doping effectively balances the heterogeneity of grain size and the distribution of the binder phase network, minimizing micropores and optimizing interface bonding, thereby achieving an excellent synergy between strength and ductility and expanding the alloy’s application potential.