Effect of mechanical alloying on microstructure and mechanical properties of Ti-24Nb-4Zr-3Mn alloys prepared by spark plasma sintering

In the present study, Ti-24Nb-4Zr-3Mn alloys were prepared by mechanical alloying and spark plasma sintering. With the increase of milling time, the particle size of alloy powder decreases, while the oxygen content shows the opposite trend. The excess O content will dramatically deteriorate the mechanical properties of Ti-24Nb-4Zr-3Mn alloy and should be strictly controlled in future studies. Among all the investigated alloys, Ti-24Nb-4Zr-3Mn alloy prepared by 20-hour milling powder (TNZM-20) shows excellent comprehensive mechanical properties with a preferable compressive strength (~2786 MPa) and constant strain (~ 55.3%), as well as a highest tensile strength (~1148 MPa) and elongation (~11.2%), which attribute to the combined effect of almost full density, fine grain strengthening and solid solution strengthening together with dispersion strengthening provided by FCC phase. Interestingly, the excellent combination of high strength and low elastic modulus of metastable β alloy can be obtained by manipulating the content of the FCC phase, providing a new approach for fabricating high-performance metastable β Ti alloys. • Ti-24Nb-4Zr-3Mn alloys were prepared by SPS from alloy powders milled for various times. • Ti-24Nb-4Zr-3Mn alloy prepared by 20-hour milling powder shows excellent comprehensive properties. • The origination of the FCC phase has been discussed. • The strengthening mechanisms have been clarified.