Titanium alloys of the Ti.sub.3 Al type

US4292077A · kind A · utility

Assignee

• UNITED TECHNOLOGIES CORPORATION · US

Inventors

• Martin J. Blackburn · Kensington, US
• Michael P. Smith · Mississauga, CA

Key dates

• Filing date: Jul 25, 1979
• Grant date: Sep 29, 1981
• Expiry date: Jul 25, 1999

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C22C14/00
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

Titanium-aluminum-niobium alloys having narrow and critical composition ranges are disclosed. The alloys have room temperature tensile elongations of 1.5% or greater and creep strength to density ratios better than certain nickel superalloys. Thus, they may replace other heavier base alloys in many applications up to 750.degree. C. Aluminum content must be closely controlled as excess amount decreases ductility while insufficient amount decreases creep strength. Niobium content is also critical as excess amount adversely affects creep strength-to-density ratio while insufficient amount decreases ductility. And there is an important interrelationship between niobium and aluminum. Disclosed are alloys having atomic percent compositions of 24-27 Al, 11-16 Nb, balance Ti; more preferred are alloys of 24.5-26 Al, 12-15 Nb, balance Ti. (Nominally, these alloys in weight percent are Ti-13/15Al-19.5/30Nb and Ti-13.5/15Al-25/28Nb.) Vanadium is uniquely found to be substitutional for niobium in the foregoing alloys in amounts up to 4 atomic percent, thereby reducing density and increasing strength-to-density ratio while maintaining properties. Mechanical properties are dependent on heat trea…