Microstructure and mechanical properties of TaNbTiZr refractory high-entropy alloy fabricated by EBM
Refractory high-entropy alloys(RHEAs)exhibit excellent high-temperature performance and have broad application prospects in aerospace,nuclear energy,and other fields.However,it is difficult to prepare RHEAs through conventional manufacturing methods because of the high melting points of the constituent elements.In this study,high-quality TaNbTiZr RHEA spherical powders prepared by plasma rotating electrode process(PREP)were used as raw materials to fabricate the TaNbTiZr RHEA by electron beam melting(EBM).The effects of process parameters on the microstructure and mechanical properties were investigated by orthogonal experiments.The results show that the density of the EBMed samples increase initially and then decrease with the increase of energy density,and the EBMed sample at an energy density of 37.5 J/m has the highest relative density of 98%.The TaNbTiZr RHEA consists of fine equiaxed grains on both the XOY and XOZ planes,with average grain sizes of 6.32 μm and 6.93 μm,respectively.There are(Nb,Ta)-rich BCC1 matrix phase and Zr-rich BCC2 network phase inside the grains.The TaNbTiZr RHEA exhibits excellent mechanical properties,with yield strength,tensile strength,and elongation of 988 MPa,1173 MPa,and 3.99%,respectively.Theoretical calculation shows that the high yield strength of the TaNbTiZr RHEA is mainly due to the effects of high lattice distortion strengthening and high grain boundary strengthening.
refractory high-entropy alloyselective electron beam meltingmicrostructuremechanical property
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