Single crystal seed alloy

• US 20020007778A1
• Filed: 05/18/2001
• Published: 01/24/2002
• Est. Priority Date: 05/20/2000
• Status: Active Grant

• Current Assignee: Rolls-Royce PLC (Rolls-Royce Holdings Plc)
• Original Assignee: Rolls-Royce PLC (Rolls-Royce Holdings Plc)
• Inventors: Ford, David A., Hill, Anthony D.
• Granted Patent: US 6,740,176 B2
• Time in Patent Office: Days
• US Class Current: 117/1
• CPC Class Codes: C30B 11/00 Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method C30B13/00, C30B15/00, C30B17/00, C30B19/00 take precedence; under a protective fluid C30B27/00
• CPC Class Codes: C30B 11/14 characterised by the seed, e.g. its crystallographic orientation
• CPC Class Codes: C30B 29/52 Alloys

Abstract

An alloy composition suitable for use as a single crystal seed comprises nickel and, in the proportion of 5 to 50 weight %, a further metal selected from the Transition Series of elements in Period VI of the Periodic Table of Elements. The further metal may be tungsten or tantalum. The alloy composition contains no component which forms an oxide layer at elevated temperatures, and in particular contains no aluminium or titanium. The alloy composition is suitable for use as a seed alloy for the casting of single crystal components such as aerofoils for gas turbine engines.

Claims

1. A single crystal seed alloy composition comprising:

nickel; and

,

in the proportion of 5 to 50 weight, % a further metal selected from the Transition Series of elements in Period VI of the Periodic Table of elements.

2. A single crystal seed alloy composition as claimed in claim 1, which alloy composition has a solidification temperature which is not less than 1300°

C. and not greater than 1400°

C.

3. A single crystal seed alloy composition as claimed in claim 1 consisting essentially of nickel and the further metal.

4. A single crystal seed alloy composition as claimed in claim 1, wherein the further metal is present in the range 13 to 50 weight %.

5. A single crystal seed alloy composition as claimed in claim 1, wherein the alloy composition forms substantially no oxide layer when molten.

6. A single crystal seed alloy composition as claimed in claim 1, which alloy composition contains no aluminium.

7. A single crystal seed alloy composition as claimed in claim 1, which alloy composition contains no titanium.

8. A single crystal seed alloy composition as claimed in claim 1, wherein the alloy has a solidification temperature range not greater than 50°

C.

9. A single crystal seed alloy composition as claimed in claim 8, wherein the alloy has a solidification temperature range not greater than 20°

C.

11. A single crystal seed alloy composition as claimed in claim 1, wherein the further metal comprises tungsten in the range 5 to 50 weight %.

12. A single crystal seed alloy composition as claimed in claim 11, wherein the tungsten is present in the range 13 to 40 weight %.

14. A single crystal seed alloy composition as claimed in any one of claim 1, wherein the further metal comprises tantalum in the range 5 to 50 weight %.

15. A single crystal seed alloy composition as claimed in claim 14, wherein the tantalum is present in the range 13 to 50 weight %.

16. A single crystal seed alloy composition as claimed in claim 15, wherein the tantalum is present in the range 20 to 45 weight %.

17. A single crystal seed alloy composition as claimed in claim 16, wherein the tantalum is present in the range 25 to 35 weight %.

10. A single crystal seed alloy composition comprising;

nickel; and

,

in the proportion of 5 to 50 weight, % a further metal selected from the Transition Series of elements in Period VI of the Periodic Table of elements,

wherein the alloy composition has a solidification temperature which is not less than 1300°

C. and not greater than 1400°

C., and a solidification temperature range which is not greater than 20°

C.

13. A single crystal seed alloy composition consisting essentially of:

nickel; and

,

tungsten in the proportion of 13 to 40 weight %,

wherein the alloy composition has a solidification temperature which is not less than 1300°

C. and not greater than 1400°

C., and a solidification temperature range which is not greater than 20°

C.

18. A single crystal seed alloy composition consisting essentially of:

nickel; and

,

tantalum in the proportion of 25 to 35 weight %,

wherein the alloy composition has a solidification temperature which is not less than 1300°

C. and not greater than 1400°

C., and a solidification temperature range which is not greater than 20°

C.