W-Ni-Fe-Mo/Co梯度结构钨合金的制备及力学性能OA

Gradient-structured tungsten heavy alloys with spatially graded mechanical properties can effectively resolve the strength-ductility trade-off in conventional homogeneous tungsten alloys.The high-strength 93W-Ni-Fe-Mo alloys and high-ductility 90W-Ni-Fe-Co alloys were separately developed through the optimized design.The co-sintering was employed to fabricate the gradient-structured tungsten alloys,and the microstructural characteristics and mechanical properties of the W-Ni-Fe-Mo/Co alloy systems and the W-Ni-Fe gradient-structured alloys were systematically investigated.In the results,the addition of Mo can effectively improve the tensile strength of 93W-Ni-Fe alloys and the introduction of Co can improve the ductility of 90W-Ni-Fe alloys.Being fabricated by integrated pre-sintering and stepwise sintering at 1480 ℃,the gradient tungsten alloys show about 20 μm interfacial layers.Tensile tests reveal the 1153.0 MPa strength(13.1％elongation)in the high-strength zone and the 972.6 MPa strength(21.5％elongation)in the high-ductility zone.The grain refinement and solid solution strengthening mechanisms are induced by Mo doping,however,the introduction with high content(Mo mass fraction ≥ 12％)can lead to the formation of MoNi intermetallic compounds at the W/γ binder phase interface,which can damage the plasticity.