US 2007/0175551 A1Published application

Method of heat treating titanium aluminide

AssigneeROLLS-ROYCE plc

InventorsWayne E Voice, Dawei Hu, Xinhua Wu, Michael Loretto

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Abstract

A gamma titanium aluminide alloy consisting of 46 at % aluminium, 8 at % tantalum and the balance titanium plus incidental impurities has an alpha transus temperature Tα between 1310° C. and 1320° C. The gamma titanium aluminide alloy was heated to a temperature T1=1330° C. and was held at T1=1330° C. for 1 hour or longer. The gamma titanium aluminide alloy was air cooled to ambient temperature to allow the massive transformation to go to completion. The gamma titanium aluminide alloy was heated to a temperature T2=1250° C. to 1290° C. and was held at T2 for 4 hours. The gamma titanium aluminide alloy was air cooled to ambient temperature. The gamma titanium aluminide alloy has a fine duplex microstructure comprising differently orientated alpha plates in a massively transformed gamma matrix. The heat treatment reduces quenching stresses and allows larger castings to be grain refined.

Claims25

Dependent claims

A method of heat-treating titanium aluminide alloy, the titanium aluminide alloy having a single alpha phase field and being capable of producing a massively transformed gamma microstructure, the titanium aluminide alloy comprises at least 45 at % aluminium, 0-6 at % niobium, 4-10 at % tantalum, niobium plus tantalum is less than or equal to 10 at % and the balance titanium and incidental impurities, the method comprising the steps of :

(a) heating a titanium aluminide alloy to a temperature above the alpha transus temperature,
(b) maintaining the titanium aluminide alloy at a temperature above the alpha transus temperature in the single alpha phase field for a predetermined time period,
(c) cooling the titanium aluminide alloy from the single alpha phase field to produce a massively transformed gamma microstructure,
(d) heating the titanium aluminide to a temperature below the alpha transus temperature in the alpha and gamma phase field,
(e) maintaining the titanium aluminide at the temperature below the alpha transus temperature for a predetermined time period to precipitate alpha plates in the massively transformed gamma microstructure such that a refined microstructure is produced,
(f) cooling the titanium aluminide to ambient temperature.

3 more elements

Dependencies are inferred from the claim text.