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Strategic Metals Use in the Gas
Turbine Industry - Challenges
and Opportunities.
Colin Small.
© 2011 Rolls-Royce plc
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 70 years of development.
 Metals and applications.
 Challenges.
 Solutions?
 Conclusions.
© 2011 Rolls-Royce plc
 70 years of development.
 Metals and applications.
 Challenges.
 Solutions?
 Conclusions.
© 2011 Rolls-Royce plc
 Whittle W1 1941.
Weight 700 lbs.
 Thrust to weight ratio 1.2:1.
 Gas temperature around 600ºC.
 Turbine blade material.
Ni-20Cr

 Trent 1000 2011.
Weight 11924lbs.
 Thrust to Weight ratio 5.4:1.
 Gas temperature in excess of 1800°C.
 Turbine blade material.
Ni-9.6Co-6.5Ta-6.4Cr-6.4W-5.6Al-3Re-1Ti

Image © Rolls-Royce plc
© 2011 Rolls-Royce plc
5
© 2011 Rolls-Royce plc
Alloying additions to Turbine Blades.
1st
Generation
SX
Conventionally Cast
20
18
2nd
Generation
SX
3rd
Generation
SX
4th
Generation
SX
Cr
Composition (wt. %)
16
14
Co
12
10
8
Ta+W
Mo
6
4
Ru
Ti
Re
2
Al
0
1955
1965
1975
Year
1985
1995
Source: R C Reed, Superalloys: Fundamentals and Applications, Cambridge University Press, 2005
© 2011 Rolls-Royce plc
2005
 70 years of development.
 Metals and applications.
 Challenges.
 Solutions?
 Conclusions.
© 2011 Rolls-Royce plc
Strategic Metals In Gas Turbines.
Alloying
Application
Applications
Typical Components
Ni, and Co-based
superalloys
Ni, and Co-based
superalloys
Compressor, combustor, HP and LP turbine,
exhaust
Compressor, combustor, HP and LP turbine,
exhaust
Hafnium
Ni-based superalloys
Compressor, combustor, HP turbine, exhaust
Niobium
Ni-based superalloys
Platinum
Coatings
Coatings
Magnetic Materials
Ni-based SX alloys
HP turbine
Combustor, HP turbine, exhaust
Ancillaries
HP turbine
Blades, discs, casings, structural
components
Blades, discs, casings, structural
components
Blades, discs, casings, structural
components
Blades, disc and structural
components
SX blades
Thermal barrier coatings
Permanent magnets
SX blades
Ni-based SX alloys
HP turbine
Not used - too scarce/expensive
Tantalum
Ni-base superalloys,
metallic metal
Compressor, HP turbine, exhaust, electronics
Blades, discs, casings, structural
components, electrical capacitors
Titanium
Ti-based alloys
Compressor
Tungsten
Ni-based superalloys
Compressor, combustor, HP and LP turbine,
exhaust
Vanadium
Ti-based alloys
Compressor
Material
Cobalt
Chromium
Rare Earths
Rhenium
Ruthenium
© 2011 Rolls-Royce plc
Compressor, and LP turbine
Blades, disc and structural
components
Blades, discs, casings, structural
components
Blades, discs, structural
components
Compressor
blades
Cobalt
Chromium
Niobium
Tantalum
Titanium
Tungsten
Vanadium
Ancillaries
and Control
Systems
Cobalt
Rare Earths
Tantalum
© 2011 Rolls-Royce plc
Use of Strategic
Metals
Compressor
LP Turbine
Discs
Blades
Cobalt
Cobalt
Chromium
Chromium
Hafnium
Niobium,
Tantalum
Tantalum
Titanium
Tungsten
Tungsten
Vanadium
Combustor
Cobalt
Chromium
Rare Earths
Tungsten
In Combat
Engines
HP Turbine
Discs
Cobalt
Chromium
Tantalum
Tungsten
HP Turbine Blades
Cobalt
Chromium
Hafnium
Platinum
Rhenium
Rare Earths
Tantalum
Tungsten
Exhaust
Cobalt
Chromium
Rare Earths
Tungsten
LP Turbine
Discs Cobalt
Chromium
Niobium
Tantalum
Tungsten
Image © Eurojet Turbo GmbH
 70 years of development.
 Metals and applications.
 Challenges.
 Solutions?
 Conclusions.
© 2011 Rolls-Royce plc
Challenges.
 Availability/Costs.
 Aerospace requirements.
 Materials usage.
Image © Rolls-Royce plc
© 2011 Rolls-Royce plc
Availability & Costs.
 Scare resources cost
more money.
 Scarcity, real or
perceived?
 Is your demand
significant?
 What is the cost of
qualifying a new
material?
Image © Rolls-Royce plc
© 2011 Rolls-Royce plc
Aerospace Requirements.
 Changes must not invalidate
certified products.

Aerospace has a huge legacy
product range to deal with.
 Traditional materials have
decades of performance data
behind them.

Limited opportunity to use new
technology to backfill on mature
products
 Key issue – We must be able to
state that the new material will
perform as well as the traditional
material for life required
© 2011 Rolls-Royce plc
Images © BAe Systems
Material Usage.
For a large engine we typically require……
6 tonnes of Titanium
9 tonnes of Nickel
6.5 tonnes of Steel
… to make a 6 tonne engine.
© 2011 Rolls-Royce plc
 70 years of development.
 Metals and applications.
 Challenges.
 Solutions?
 Conclusions.
© 2011 Rolls-Royce plc
Solutions?
 Do not use.
 Minimise.
 Substitute.
 Recycle.
 New alloys.
© 2011 Rolls-Royce plc
Image © Rolls-Royce plc
 Do not use.

Preferred strategy, e.g. Ru.
- 1 – 3% addition to alloy to current
generation of SX alloys to
improved performance (very
effective).
- Cost is volatile, $170 per troy
ounce in 2011 but has reached
$573 in 2007.
- World production could not meet
demand if used in SX blades.
- Will not be used in SX blades.

Not usually possible in
established alloys
(requalification cost).
© 2011 Rolls-Royce plc
Image © Rolls-Royce plc
 Minimise.


Possibly as alloy composition is a
balance of properties.
Need to understand the important
properties and tailor chemistry for
those, e.g. Re.
- Alloy element for 3rd and 4th
generation SX alloys.
- Original alloy design intent was
to maximise creep resistance.
- Service shows we don’t use full
creep life but that
environmental performance is
a major issue.
- Redesign of alloy to meet the in
service need – reduce rhenium
content .
© 2011 Rolls-Royce plc
Image © Rolls-Royce plc
 Substitute

Sometimes possible.
 Recycle


OK if bulk addition.
Nearly impossible if in trace (ppm)
quantities in small components.
 New alloys



Design alloy with cost and supply as
constraints as well as the usual
property and environmental
constraints.
Opens up new areas of metallurgy
Challenge is that these alloys do not
have the traditional balance of
engineering properties – need to
educate designers and engineers to
think differently.
© 2011 Rolls-Royce plc
Image © Rolls-Royce plc
 70 years of development.
 Metals and applications.
 Challenges.
 Solutions?
 Conclusions.
© 2011 Rolls-Royce plc
Conclusions.
 Use of strategic materials is a challenge
to the aerospace industry.
 Need to understand what is making it a
strategic metal before you can address
the issues.
 Number of strategies are available to
limit use of such metals but it depends
on the applications if any of these can be
used.
© 2011 Rolls-Royce plc