Microstructures and mechanical properties of Mn modified, Ti-Nb-based alloys

Ti-16Nb-xMn (x = 0, 1, 3, 5, 7, and 9 at.%) alloys were prepared by cold crucible levitation melting, and their tensile properties were studied at ambient temperature. The Ti-16Nb-7Mn alloy exhibited a high tensile strength of 695 MPa, large plastic strain of 43%, and low elastic modulus of 77 GPa. Transmission electron microscopy studies revealed that orthorhombic α″ and body-centered cubic β phases present in the Ti-16Nb alloy were modified by the addition of Mn to form a single β phase structure. The improvement in the mechanical properties with the addition of Mn is attributed to three factors: (1) the change of phase constitutions from α″+β to β+ω, then to β, (2) solid solution strengthening, and (3) increased stability of the β phase. The Ti-16Nb-7Mn alloy displayed high strength, high ductility, and low elastic modulus, making it a promising candidate for biomedical applications. - Highlights: • Ti-16Nb-1Mn alloy (at.%) consisted of α″ and ω phases in addition to β phase. • Ti-16Nb-xMn (x = 7 and 9 at.%) alloys exhibited a single β phase structure. • Addition of 7 and 9 at.% Mn increased both strength and ductility of Ti-Nb alloys. • The Ti-16Nb-7Mn (at.%) alloy exhibited the lowest elastic modulus of 77 GPa.