Abstract: A process for the production of a superelastic material out of a nickel and titanium alloy, characterized by the fact that it consists in obtaining an ingot starting from a mixing of nickel and titanium consisting in 55.6%.+-.0.4% in weight of nickel and to proceed with a thermal treatment of martensite plaquettes generation by subjecting said ingot during 5 to 45 minutes to a temperature comprised between 480 and 520.degree. C. The process allows the obtaining of a truly superelastic material at room temperature.

Abstract: A titanium alloy part having a structure comprising ex-beta acicular grains and with equi-axial alpha phases gathered in a plurality of rows at boundaries of the grains. The alloy comprises, by weight, 2 to 5% Mo, 3.5 to 6.5% Al, 1.5 to 2.5% Sn, 1.5 to 4.8% Zr, Fe.ltoreq.1.5%, 4 to 12% Mo+V+Cr, and the balance, titanium and impurities.

Abstract: A method of producing a part having high strength and improved ductility from a titanium alloy having a composition, in percent by weight, or Mo equivalent 5 to 13 and Al equivalent 3 to 8, the balance being titanium and impurities, comprising the steps of hot working an ingot of the alloy including a roughing down under heat and preparation of a blank under heat, preheating to a temperature situated above the real beta transus of the hot worked alloy, and then final working of at least a part of this blank, after which the blank obtained is subjected to a solution heat treatment and then aged. The hot worked blank is cooled from the preheating temperature to a temperature for the beginning of final working which, under the conditions of the cooling of the blank, is at least 50.degree. C. below the real beta tansus and at least 10.degree. C. above the temperature of appearance of the alpha phase, so that the final working is sufficient to end within the alpha nucleation range.

Abstract: A process is disclosed for improving the ductility of shape-memory alloy products based on Ti-Ni involving martensitic transformation. The process comprises at least one thermal treatment cycle of alternating hot and cold treatment, wherein the first thermal treatment cycle comprises a cold treatment at a temperature both lower than -50.degree. C. and lower than M.sub.s -50.degree. C., where M.sub.s is the temperature at which martensitic transformation of the product begins, and a hot treatment of the product at a temperature of 700.degree. to 900.degree. C. Each optional subsequent thermal treatment cycle comprises a cold treatment of the product at a temperature both lower than -50.degree. C. and lower than M.sub.s -30.degree. C., and a hot treatment of the product at a temperature of 600.degree. to 900.degree. C.

Abstract: A wrought and heat treated titanium alloy part is disclosed having the composition, by w eight, Al 4.5 to 5.4%, Sn 1.8 to 2.5%, Zr 3.5 to 4.8%, Mo 2.0 to 4.5%, Cr 1.5 to 2.5%, Cr+V 1.5 to 4.5%, Fe 0.7 to 1.5%, O 0.07 to 0.13%, the remainder being Ti and impurities. The part is characterized by a fine and regular alpha-beta structure and essentially segregation free microstructures, and has the mechanical characteristics: Rm.gtoreq.1200 MPa, R.sub.p0.2 .gtoreq.1000 MPa, A%.gtoreq.5, K.sub.1c at 20.degree. C..gtoreq.45 MPa..sqroot.m, creep at 400.degree. C. under 600 MPa:0.5% in more than 200 hours.

Abstract: The process according to the invention comprises the following stages:(a) an ingot of the following composition is produced (% by weight): Al 3.8 to 5.4, Sn 1.5 to 2.5, Zr 2.8 to 4.8, Mo 1.5 to 4.5, Cr<2.5 and Cr+V 1.5 to 4.5, Fe<2.0, Si<0.3, 0<0.15, the remainder being Ti and impurities;(b) the ingot undergoes hot working, comprising a rough-shaping and then a final working preceded by preheating in the beta range;(c) the blank of the part obtained is solid solution heat treated by maintaining it at a temperature 10.degree. to 40.degree. C. lower than its real "beta transus";(d) ageing for 4 to 12 h at between 550.degree. and 650.degree. C. is then carried out on the blank of the part or the part itself.The invention also relates to the process and the parts obtained under preferred conditions, said parts having in particular a good mechanical strength (Rm and R.sub.p0.2 respectively at least equal to 1200 and 1100 MPa), a good tenacity and a good creep resistance at 400.degree. C.