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A new study from Yale University’s School of Forestry and Environ-
mental Studies, New Haven, Conn., investigates potential substitutes
for 62 metals as some of these materials are becoming harder to source.
The study, “On the Materials Basis of Modern Society,” was recently pub-
lished in the Proceedings of the National Academy of Sciences and reaches
a few dire conclusions. The authors state, “The situation need not inspire
panic, but should stimulate more diligent and comprehensive approaches
to the balance between supply and demand across the entire periodic
table.” For a dozen different metals, potential substitutes for their main
applications are either inadequate or do not exist.
The report begins with a stark reminder that not even a century ago,
fewer than 12 materials were in widespread use—wood, brick, iron, cop-
per, gold, silver, and a few plastics. Contrast that to today’s multi-material
products, for example, where a modern computer chip contains more
than 60 different elements
selected by product design-
ers and materials scientists
for enhanced performance.
Another example looks at
the increased diversity of
superalloy metals used in
aircraft turbine blades.
These nickel-rich alloys
were developed with vari-
ous alloying elements over
the years to achieve greater corrosion resistance and stability at higher
temperatures. The result is increased engine operating temperatures and
higher efficiency, made possible by a complex mix of materials. Re-
searchers contend that other modern products followed similar perform-
ance evolutions, i.e., faster computers and better medical images, but
worry about suitable substitutes as some elements are becoming scarcer.
The Yale study also points to other studies on this topic, such as the
2008 National Research Council’s Minerals, Critical Minerals, and the
U.S. Economy. Further, it explores a few examples where substitute mate-
rials were successfully used. For example, when the cobalt supply was
threatened in the 1970s due to a civil war in Zaire, scientists at the Gen-
eral Motors Research Laboratories and colleagues developed cobalt-free
substitute magnets that worked well. Another case involves a rhenium
shortage that impacted the superalloys used in gas turbines. Scientists at
the General Electric Research Laboratories developed alternative alloys
containing little or no rhenium. However, the study points out that these
may be exceptions. For example, some widely used metals such as copper,
chromium, manganese, and lead have no good substitutes available for
their major uses. Others that have very low substitute performance poten-
tial include rhenium, rhodium, lanthanum, europium, dysprosium,
thulium, ytterbium, yttrium, strontium, and thallium. The authors assert
that substitution by a different material is likely to decrease product
performance, raise prices, or both. For more information, visit
ADVANCED MATERIALS & PROCESSES • FEBRUARY 2014 4
spot l ight feedback
market
Study explores substitutes
for 62 scarce metals
Single crystal clarifications
Thank you to all who sent emails re-
garding my article on the development of
single crystal superalloys (September
2013). Four items need to be clarified or
corrected: 1) Fan materials today include
titanium alloys and composites; 2) Herb
Hershenson was hired to run the chem-
istry group and later hired Bill Goward to
oversee coatings, oxidation, and corro-
sion; 3) the Air Force Office of Scientific
Research contract on the study of single
crystal superalloys originally had Gerry
Leverant as the principal investigator.
Shortly after Gerry left Pratt & Whitney,
the Statement of Work was revised to
focus on the mechanism of Re strength-
ening as well as the identification of
lower and upper limits of Re to provide
enhanced creep resistance without the
risk of forming undesirable phases; and
4) the Navy contract to run single crystal
turbine blades in the PT6 was actually
under the Naval Air Propulsion Center,
with Joe Glatz as program manager.
Tony Giamei
Seeking dome details
I am a civil engineering student at the
University of Ghent in Belgium. We have
a project-based assignment for a course
in spatial structures and are very inter-
ested in the geodesic dome, as in your
Facebook page cover photo. We must
explain how the forces are transmitted
into the structure and also need to create
a scale model. Can you provide some in-
formation about the structure, such as
dimensions, construction details, or
other information about the principles of
the design?
Björn Noyelle, via ASM’s Facebook page
[The design of Materials Park was the
vision of William Hunt Eisenman, ASM’s
managing director from 1918 through
1958, Cleveland architect John Terence
Kelly, and inventor R. Buckminster
Fuller. Within the park, the geodesic
dome was engineered and created by
R. Buckminster Fuller. It is the largest
dome of its kind and was one of his fa-
vorites. Made of extruded aluminum
pipe, the open-work structure stands
103 ft high and 250 ft in diameter,
weighs 80 tons, and has more than
65,000 parts. The dome stands on five
pylons, two of which rise up from court-
yards set into the building.—Eds.]
We welcome all comments
and suggestions. Send letters to
.
Elements
shown in
red, such
as rhenium
and lead,
appear to
have very
poor
substitution
potential,
which will
likely have a
negative
impact on
product
performance
and price.