Abstract: Provided is a beta-type titanium alloy having a low elastic modulus and a high strength. The titanium alloy includes 6 to 13 wt % of Mo, 0.1 to 3.9 wt % of Fe, a remaining amount of Ti, and inevitable impurity, and selectively includes 0.1 to 3.9 wt % of Al. The titanium alloy according to the present invention has a high tensile strength of greater than or equal to 1,300 MPa and a low elastic modulus of less than or equal to 95 GPa at low cost.

Abstract: Disclosed is a method capable of inexpensively forming a gradient-hardened rigid layer which has characteristics of functionally graded material on the surface layer of titanium. The method includes (a) injecting titanium into a heat treatment apparatus and performing ventilation to maintain an atmospheric pressure of 10?4 torr or less, (b) performing a pretreatment process of heating the titanium at 730 to 800° C. for 10 minutes to 5 hours to remove an oxide film formed on the surface of the titanium, (c) injecting one or more gases selected from nitrogen, oxygen, and carbon into the heat treatment apparatus and heating the titanium at 740 to 950° C. for 30 minutes to 20 hours such that a gradient-hardened rigid layer having a concentration gradient of the gases is formed on the surface of the titanium, and (d) cooling the titanium.

Abstract: A process as described for treating Ti.sub.3 Al-based alloys comprising, in ddition to titanium and aluminum as .alpha.-phase-stabilizing element, niobium and further elements stabilizing the .beta.-phase in an amount of from 20 to 30% by weight, wherein the further elements stabilizing the .beta. phase are present in an amount of at least 4% by weight by(a) preparing the alloys by melting or via the powder-metallurgical route,(b) deforming at a temperature within the (.alpha..sub.2 +.beta.)-phase area by more than 60% in one or more steps with stress-relief annealing without complete recrystallization effected between these steps,(c) solution annealing the formed part for from 5 minutes to 120 minutes below the .beta.-transus temperature of the alloy,(d) quenching, and(e) subsequent aging/stress-relief annealing at temperatures within the range of from 500.degree. for 75.degree. C. for from 0.5 to 24 hours.