Defense Intelligence Reference Document Materials For Advanced Aerospace Platforms

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design of a cryopump potentially can benefit from these new materials and from
abandoning the use of notched strength as a design paradigm.
The combustion chamber of a rocket engine is made from a copper alloy and is cooled
by passing liquid hydrogen through channels in the outer wall. The space shuttle main
engine combustion chamber is made of NARloy-Z, a Cu-3%Ag-0.5%Zr alloy that has
excellent thermal conductivity and better strength than the commercially available Cu-
0.15%Zr alloy known as AMZIRC. While a lighter combustion chamber would be
welcome, developing hydrogen-resistant turbine materials would be a much better use
of available rocket engine alloy development resources.
SUMMARY AND RECOMMENDATIONS
This document has attempted to review a range of materials that may have promise for
all aspects of aerospace platforms. Because of the breadth of this topic, discussion has
focused on opportunities and associated risks, but with little technical detail. Practical
issues such as manufacturing capabilities and costs and the availability of materials also
have been addressed where appropriate. Another recurring issue is the ability to
achieve better design efficiency through a design synthesis process that concurrently
treats form, fit and function, manufacturing capability, and materials capability as
equally important design constraints. Although this approach has yet to be successfully
used for a major high-performance structure project, engineering is nearing a state of
development where it may now be feasible.
If the space shuttle is used as a benchmark, it is clear that numerous opportunities will
exist to improve structural efficiency. This possibility reflects the progress made since
the shuttle and its engine were designed. Improved durability and reduced operating
cost also are possible. The issue of long lead time holding back these improved design
methods is most often one of timely availability of new, attractive materials that are
mature enough to be used in a system without increasing the risk of failure. The
materials community is actively developing and using computational models and
simulation methods to address this concern. Despite some progress, further advances
are required to bring computational materials engineering to the desired level of
maturity.
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2. Chawla K. Composite Materials, Science and Engineering 2nd edition. Springer, 1998;
3. Baker, A., Dutton, s. and Kelly, D. Composite Materials for Aircra~ Structures 2nd edition. AIAA, 2002.
4. Lutjering, G and Williams, J. Titanium, 2nd edition. Springer, 2007,
s. Sims, C. and Hagel, W. The Superalloys. Wiley, 1972.
6, Mishra, R. and Ma, z. Friction Stir Welding and Processing, Materlals Science and Engineering. v.so, pp. 1-78,
2005.
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