BCC MATERIALS OF TITANIUM, ALUMINUM, NIOBIUM, VANADIUM, AND MOLYBDENUM, AND PRODUCTS MADE THEREFROM

Abstract

New beta-style (bcc) titanium alloys are disclosed. The new alloys generally include 4-8 wt. % Al, 4-8 wt. % Nb, 4-8 wt. % V, 1-5 wt. % Mo, optionally 2-6 wt. % Cr, the balance being titanium, 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: 4-8 wt. % Al; 4-8 wt. % Nb; 4-8 wt. % V; 1-5 wt. % Mo; and optionally 2-6 wt. % Cr; the balance being Ti, optional incidental elements, and unavoidable impurities.

2. The titanium alloy of claim 1, wherein the titanium alloy includes a sufficient amount of the Ti, the Al, the Nb, the V, the Mo, and the optional Cr to realize a beta transus temperature of not greater than 850° C.

3. The titanium alloy of claim 1, wherein the alloy includes at least 5.0 wt. % Al.

4. The titanium alloy of claim 3, wherein the alloy includes not greater than 7.0 wt. % Al.

5. The titanium alloy of claim 1, wherein the alloy includes at least 5.0 wt. % Nb.

6. The titanium alloy of claim 5, wherein the alloy includes not greater than 7.0 wt. % Nb.

7. The titanium alloy of claim 1, wherein the alloy includes at least 5.0 wt. % V.

8. The titanium alloy of claim 7, wherein the alloy includes not greater than 7.0 wt. % V.

9. The titanium alloy of claim 1, wherein the alloy includes at least 2.0 wt. % Mo.

10. The titanium alloy of claim 9, wherein the alloy includes not greater than 4.0 wt. % Mo.

11. The titanium alloy of claim 1, wherein the alloy includes 2-6 wt. % Cr.

12. The titanium alloy of claim 11, wherein the alloy includes at least 3.0 wt. % Cr.

13. The titanium alloy of claim 12, wherein the alloy includes not greater than 5.0 wt. % Cr.

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

15. 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.

16. A method comprising: (i) using a feedstock in an additive manufacturing apparatus, wherein the feedstock comprises: 4-8 wt. % Al; 4-8 wt. % Nb; 4-8 wt. % V; 1-5 wt. % Mo; and optionally 2-6 wt. % Cr; the balance being Ti, optional incidental elements, and unavoidable impurities; (ii) producing a metal product in the additive manufacturing apparatus using the feedstock.

17. The method of claim 16, 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.

18. The method of claim 16, 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.

19. The method of claim 16, comprising cooling at a rate sufficient to form at least one precipitate phase, wherein the at least one precipitate phase comprises Ti.sub.3Al.

20. The method of claim 19, wherein the metal product comprises at least 0.5 vol. % of Ti.sub.3Al.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] FIG. 1 is a schematic illustration of bcc, fcc, and hcp unit cells.

[0051] FIG. 2a is a graph showing the effect of Al content on the equilibrium phase fields of a Ti-3Mo-6Nb-6V-XAl alloy.

[0052] FIG. 2b is a graph showing the effect of V content on the equilibrium phase fields of a Ti-6Al-3Mo-6Nb-XV alloy.

[0053] FIG. 2c is a graph showing the effect of V content on the equilibrium phase field of Ti-6Al-3Mo-6V-XNb

[0054] FIG. 2d is a graph showing the effect of Mo content on the equilibrium phase fields of a Ti-6Al-6V-6Nb-XMo alloy.

[0055] FIG. 2e is a graph showing the effect of Cr content on the equilibrium phase fields of a Ti-6Al-6V-6Nb-3Mo-XCr alloy.

[0056] FIG. 3 is a flow chart of one embodiment of a method to produce a new material

[0057] FIG. 4 is a flow chart of one embodiment of a method to obtain a wrought product having a bcc solid solution structure with one of more precipitates therein.

DETAILED DESCRIPTION

Example 1: Testing of Invention and Conventional Alloys

[0058] Two invention alloys (Ti-6Al-3Mo-6Nb-6V, and Ti-6Al-3Mo-6Nb-6V-4Cr), 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 3-5. Specimens of the Ti-6Al-3Mo-6Nb-6V and Ti-6Al-3Mo-6Nb-6V-4Cr alloys were heat treated at 500° C. for 8 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 also shown. Tensile properties at 650° C. were also tested for the Ti-6Al-3Mo-6Nb-6V-4Cr alloy and are also provided in the Table 5, below.

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

TABLE-US-00005 TABLE 4 Ti-6Al—3Mo—6Nb—6V Properties Condition TYS (MPa) UTS (MPa) Elong. (%) As-Cast 789 979 8 Heat Treated N/A 937 N/A

TABLE-US-00006 TABLE 5 Ti—6Al—3Mo—6Nb—6V—4Cr Properties Condition TYS (MPa) UTS (MPa) Elong. (%) As-Cast 941 942 — Heat Treated 1480 1488 — As-Cast, Elevated Temp. 238 417 16 Heat Treated, Elevated Temp 234 415 16
As shown, the new invention alloys realized improved properties as compared to the conventional alloy.

[0059] 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.