TITANIUM ALLOY HAVING HIGH STRENGTH AND SUPER-LOW ELASTIC MODULUS
The present invention relates to a titanium alloy which is capable of nonlinear elastic deformation and simultaneously has super-high strength, super-low elastic modulus and stable super-elastic properties. The titanium alloy according to the present invention comprises Nb, Zr and O as alloy elements, the remainder being Ti and inevitable impurities, and has a valance electron ratio (e/a) of 4.17 to 4.22, a Mo equivalent (Mo eq ) of 7.50 to 9.72, and an Al equivalent (Al eq ) of 1.42 to 14.53.
1 . A titanium alloy comprising Nb, Zr and O as alloying elements, with a remainder being Ti and inevitable impurities, the titanium alloy having an electron/atom (e/a) ratio of 4.17-4.22, a Mo equivalent (Mo eq ) of 7.50-9.72, and an Al equivalent (Al eq ) of 1.42-14.53.
2 . The titanium alloy of claim 1 , having an electron/atom (e/a) ratio of 4.19-4.21, a Mo equivalent (Mo eq ) of 8.19-9.03, and an Al equivalent (Al eq ) of 1.60-10.78.
3 . The titanium alloy of claim 1 , comprising 30-34 mass % of Nb, 5.7-9.7 mass % of Zr, and 0.03-1.0 mass % of O.
4 . The titanium alloy of claim 1 , wherein a coefficient of correlation of a decrease in superelastic elongation (%) to an increase in oxygen concentration after cold working of the titanium alloy is −0.5 (%/mass %) or more.
5 . The titanium alloy of claim 1 , having a superelastic elongation of 2.5% or more after cold working.
6 . The titanium alloy of claim 1 , having an elastic modulus of 60 GPa or less and a tensile strength of 1000 MPa or more after cold working.
7 . The titanium alloy of claim 1 , having a tensile strength (MPa)/average elastic modulus (GPa) ratio of 0.020 or more after cold working.