1. * GB780004 (A)
Description: GB780004 (A) ? 1957-07-31
An improved copper-aluminium alloy
Description of GB780004 (A)
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PATENT SPECIFICATION...
Inventor: JOHN PHILIP DENNISON Date of filing Complete Specification
Aug. 22, 1952.
Application Date May 22, 1951.
Complete Specification PublishedJuly 31, 1957.
780,004 No. 11874/51.
Index at acceptance:--Class 72, AllB; and 82(1), A(2A: 4A), A8(A1: A3:
J: K: R: Z12), A10.
International Classification:-C21d. C22c.
COMPLETE SPECIFICATION
An improved Copper-Aluminium Alloy We, N. C. ASHTON LIMITED, of St.
Andrew's Road, Huddersfield, in the County of York, a British company,
do hereby declare the invention, for which we pray that a patent may
be granted to us, and the method by which it is to be performed, to be
particularly described in and by the following statement: -
This invention relates to copper-base alloys of the single phase
(alpha) copper-aluminium type. It more particularly concerns an
improved quaternary copper-base alloy containing aluminium, cobalt,
and nickel, in which the nickel may be substituted in whole or in part
by manganese, which, by virtue of its precipitation hardening
characteristics, is capable of providing articles having high
resistance to creep at temperatures up to and including 500( C. Due to

2. these precipitation hardening characteristics the alloy also possesses
very good mechanical properties at ordinary temperatures.
The alloy according to the invention is composed of 5.5%0 to 8%
aluminium, 1%.-2% cobalt, and 2% to 6% nickel, the balance being
copper and usual impurities and the nickel being replaceable in whole
or in part by an equal weight of manganese. The alloy after suitable
treatment, for example, as described hereinafter, exhibits
exceptionally high resistance, to creep, high mechanical properties
and is capable of being worked either hot or cold. These
characteristics render the alloy suitable for a variety of purposes
requiring high tensile strength and proof stress, in particular it is
considered to be suitable for use as second stage gas turbine heat
interchanger tubes or for gas turbine compressor blades.
Preferred proportions in which to alloy the aforesaid metals are: -
aluminium 7%, cobalt 1.5%, nickel 4%, the balance being copper 40 and
usual impurities. The nickel may be substituted in whole or in part by
an equal weight of manganese.
The following description gives examples of the development of the
properties of the 45 alloy by fabrication and heat treatment.
In preparing samples of the alloy for the enumerated tests, the metals
were melted together in the requisite proportions in the conventional
manner, the cobalt and nickel 50 being added in the form of
copper-base master alloys and billets were cast 8" X 6" x 12". The
test specimens were prepared by hot rolling into suitable strip at
temperatures between 800 C., and 900 C., followed by heat treatment.
The heat treatment may consist of a solution treatment between 850 C.
and 1000 C., and the cooling rate being critical depends on the
thickness of cross section of the 60 material. This may involve air
cooling.or quenching in water. For instance, to obtain optimum
properties, materials exceeding," in thickness should be water
quenched, and materials having a thickness not exceeding x 65 should
be air cooled. The material may be precipitation-hardened in the range
400 C. to 600 C., either directly or following cold work. After cold
work, for certain purposes the precipitation-hardening 70 may be
omitted.
EXAMPLE
Nominal composition of alloy in per cent by weight, balance copper and
impurities, is 7% aluminium, 1.5 ,/. cobalt, 4% nickel. 5 [Price 3s.
6d.] K-, z 780,004 Property.
Tensile strength, Elongation % Treatment Test in tons/in2 on 2"
Solution treatment 2 hours at 950 C.
Hardened by heating 2 hours at 500 C. Mechanical 60 10 Solution
treatment 2 hours at 950 C.
Cold worked 30%.. Hardened by heating + hour at 5000 C. 65 5 Annealed

3. 5 hours at 8000 C. 38 40 Annealed 5 hours at 8000 C. Creep rupture at
4500 C. Life in hours 200.
4 tons/in2 load.
Solution treatment 2 hours at 9500 C.
Cold worked 30%.,, >1000.
Solution treatment 2 hours at 950 C. Creep at 4500 C. Steady rate
after 2 tons/in2 load. 500 hours.
0.005 %.' per day.
The alloy can be used in the forged annealed or solution treated, hot
or cold worked states, or following precipitation hardening.
S Alloys in accordance with this invention may contain up to 0.5%.
silicon.
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