ALPHA-BETA TITANIUM ALLOYS HAVING ALUMINUM AND MOLYBDENUM, AND PRODUCTS MADE THEREFROM

Abstract

New alpha-beta titanium alloys are disclosed. The new alloys generally include 7.0-11.0 wt. % Al, and 1.0-4.0 wt. % Mo, wherein Al:Mo, by weight, is from 2.0:1-11.0:1, the balance being titanium, any optional incidental elements, and unavoidable impurities. The new alloys may realize an improved combination of properties as compared to conventional titanium alloys.

Claims

1. A titanium alloy comprising: 7.0-11.0 wt. % Al; 1.0-4.0 wt. % Mo; wherein Al:Mo, by weight, is from 2.0:1-11.0:1; the balance being Ti, optional incidental elements, and unavoidable impurities.

2. The titanium alloy of claim 1, wherein the alloy includes not greater than 10.5 wt. % Al.

3. The titanium alloy of claim 1, wherein the alloy includes not greater than 10.0 wt. % Al.

4. The titanium alloy of claim 1, wherein the alloy includes not greater than 9.5 wt. % Al.

5. The titanium alloy of claim 1, wherein the alloy includes not greater than 9.0 wt. % Al.

6. The titanium alloy of claim 1, wherein the alloy includes at least 1.5 wt. % Mo.

7. The titanium alloy of claim 6, wherein the alloy includes not greater than 3.5 wt. % Mo.

8. The titanium alloy claim 6, wherein the alloy includes not greater than 3.0 wt. % Mo.

9. The titanium alloy of claim 6, wherein the alloy includes not greater than 2.5 wt. % Mo.

10. The titanium alloy of claim 7, wherein the Al:Mo, by weight, is at least 2.33:1.

11. The titanium alloy of claim 10, wherein the Al:Mo, by weight, is not greater than 10.0:1.

12. The titanium alloy of claim 10, wherein the Al:Mo, by weight, is not greater than 6.33:1.

13. The titanium alloy of claim 1, wherein the titanium alloy is a titanium alloy body.

14. The titanium alloy body of claim 13, wherein the titanium alloy body is one of an ingot, a rolled product, an extrusion, a forging, a shape casting, or an additively manufactured product.

15. The titanium alloy body of claim 13, wherein the titanium alloy body is an automotive or aerospace component.

16. The titanium alloy body of claim 15, wherein the titanium alloy body is a turbine or engine component.

17. A method comprising: (i) using a feedstock in an additive manufacturing apparatus, wherein the feedstock comprises: 7.0-11.0 wt. % Al; 1.0-4.0 wt. % Mo; wherein Al:Mo, by weight, is from 2.0:1-11.0:1; the balance being Ti, optional incidental elements, and unavoidable impurities (ii) producing a metal product in the additive manufacturing apparatus using the feedstock.

18. The method of claim 17, wherein the feedstock comprises a powder feedstock, wherein the method comprises: (a) dispersing a metal powder of the powder feedstock in a bed and/or spraying a metal powder of the powder feedstock towards or on a substrate; (b) selectively heating a portion of the metal powder above its liquidus temperature, thereby forming a molten pool; (c) cooling the molten pool, thereby forming a portion of the metal product, wherein the cooling comprises cooling at a cooling rate of at least 100° C. per second; and (d) repeating steps (a)-(c) until the metal product is completed.

19. The method of claim 17, wherein the feedstock comprises a wire feedstock, wherein the method comprises: (a) using a radiation source to heat the wire feedstock above its liquidus point, thereby creating a molten pool; (b) cooling the molten pool at a cooling rate of at least 1000° C. per second; and (c) repeating steps (a)-(b) until the metal product is completed.

20. The method of claim 17, comprising cooling at a rate sufficient to form at least one precipitate phase, wherein the at least one precipitate phase comprises Ti.sub.3Al.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] FIG. 1 is a schematic illustration of bcc, fcc, and hcp unit cells.

[0056] FIG. 2a is a graph of the solidification path of a Ti-8Al-2Mo alloy and a prior art Ti-7Al-4Mo alloy based on the Scheil model.

[0057] FIG. 2b is a graph of the effect of aluminum content on the equilibrium freezing range of a Ti-2Mo-XAl alloy.

[0058] FIG. 2c is graph of the effect of aluminum content on the equilibrium phase fields of a Ti-2Mo-XAl alloy in the solid state.

[0059] FIG. 2d is a graph of the effect of molybdenum content on the equilibrium freezing range of a Ti-8Al-XMo alloy.

[0060] FIG. 2e is a graph of the effect of molybdenum on the equilibrium phase fields of a Ti-8Al-XMo alloy in the solid state.

[0061] FIG. 3 is a flow chart of one embodiment of a method to produce a new material.

[0062] FIG. 4 is a flow chart of one embodiment of a method to obtain a wrought product having an-alpha beta solid solution structure with one of more of the precipitates therein.

DETAILED DESCRIPTION

Example 1: Testing of Ti—Al-2Mo and Conventional Ti-6Al-4V Alloys

[0063] A Ti-8Al-2Mo (7.7 wt. % Al and 1.8 wt. % Mo, the balance being Ti) and a conventional Ti-6Al-4V alloy were cast via arc melt casting into rods. After casting, mechanical properties of the as-cast alloys were measured in accordance with ASTM E8, the results of which are shown in Tables 3-4. Specimens of the Ti-8Al-2Mo alloy were solution heat treated at 940° C. for 1 hour, then water quenched, then heat treated at 565° C. for 6 hours, and then air cooled. The mechanical properties of the heat treated alloys were then tested, the results of which are shown in Table 4, below. All reported strength and elongation properties were from testing in the longitudinal (L) direction. Estimated toughness from the stress-strain curve produced during the mechanical property testing is shown below. Tensile properties at 650° C. were also tested in accordance with ASTM E21, and are also provided in the tables below.

TABLE-US-00004 TABLE 3 Ti—6Al—4V Properties Condition TYS (MPa) UTS (MPa) Elong. (%) As-Cast 715 881 11 As-Cast, 229 366 16 Elevated Temp.

TABLE-US-00005 TABLE 4 Ti—8Al—2Mo Properties Condition TYS (MPa) UTS (MPa) Elong. (%) As-Cast 792 953 7 Heat Treated 902 1006 6 As-Cast, 390 526 16 Elevated Temp. Heat Treated, 434 545 16 Elevated Temp.

[0064] While various embodiments of the new technology described herein have been described in detail, it is apparent that modifications and adaptations of those embodiments will occur to those skilled in the art. However, it is to be expressly understood that such modifications and adaptations are within the spirit and scope of the presently disclosed technology.