Dual phase equal-atomic NbTaTiZr high-entropy alloy with ultra-fine grain and excellent mechanical properties fabricated by spark plasma sintering

摘要

Super-high strength NbTaTiZr high-entropy alloys(NbTaTiZr HEAs)have been successfully fabricated by the mechanical alloying(MA)with spark plasma sintering(SPS)technology,which is 2-fold compared with that of NbTaTiZr HEAs prepared by vacuum arc melting(VAM).After the SPS process,the bulk NbTaTiZr alloy samples are provided with dual-phase body-centered cubic(BCC)structure and nanoscale grain size about 500 nm that is obviously smaller than that of NbTaTiZr HEA fabricated by VAM.When the sintering temperature is 800℃,the compressive fracture strength is the highest reaching at 2511±78 MPa.When the sintering temperature is 1000℃,the fracture strain is the highest reaching at 12.8%,and compressive fracture strength and yield strength also reach at 2274±91 MPa and 2172±47 MPa,respectively.The excellent mechanical properties of bulk NbTaTiZr alloy samples are attributed to the merits of MA and SPS,and the collaboration effect of ultra-fine grains strengthening,solid solution strengthening and interstitial solid solution strengthening.