Effect of Element Addition on the Microstructure and Mechanical Properties of Two-Step Sintered W-6Ni-4Co Alloy
The W-6Ni-4Co-2X alloys(X=Nb,Ta,Hf,Mo and Ti)were prepared by powder metallurgy technology,and the effects of adding Nb,Ta,Hf,Mo,and Ti elements on the microstructure and mechani-cal properties of W-6Ni-4Co alloy were investigated.The results show that the microstructure of the W-6Ni-4Co-2X alloys mainly includes base phase(W phase)and binder phase,and the type and content of the binder phase are related to the precipitation of dissolved W phase in the binder phase(Ni,Co)during sinte-ring.The W grains of W-6Ni-4Co-2Ta alloy and W-6Ni-4Co-2Hf alloy are in the form of irregular polygon,while the W grains of W-6Ni-4Co-2Nb alloy and W-6Ni-4Co-2Ti alloy are ellipsoidal and dispersedly dis-tributed in the binder phase.The uniform microstructure,finer grains,and good interfacial bonding of the W/binder phase in W-6Ni-4Co-2Ta alloy contribute to its superior hardness,bending strength,and yield strength.In W-6Ni-4Co-2Mo alloy,W grains are arranged in network structure,and the continuous W ske-leton structure,in synergy with the ductile binder phase,reduces the strain hardening of the alloy,contribu-ting to its excellent strain hardening resistance.Therefore,adding suitable transition metal elements to W-6Ni-4Co alloy provides an effective way for improving its mechanical properties.
W-Ni-Co alloymetal element additiontwo-step sinteringmicrostructuremechanical property
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