Documents / Report
This Defense Intelligence Reference Document from the Defense Intelligence Agency, dated 12 January 2010, is one of a series of advanced technology reports produced in FY 2009 under the Advanced Aerospace Weapon System Applications (AAWSA) program. It reviews materials for launch vehicles, space vehicles and reusable rocket engines, including aluminum alloys, polymer and metal matrix composites, titanium and nickel alloys, ceramics and titanium aluminides. It concludes that newer materials and design methods offer many ways to improve structural efficiency and cost compared with the space shuttle.
“Harder”1 page
UNCLASSIFIED/;iP8A 8PPl<11k W&& 8tJlai! ensure that any outgassing that occurs in space would not liberate any of this toxic material-at least not where it could be ingested by the crew. Al Matrix Composites Al matrix composites (AMCs) are typically made by mixing short fibers or even particulate silicon carbide (SiC) with Al alloy powder and hot-pressing or mechanically consolidating the mixture by extrusion or forging. AMCs have higher modulus and strength but suffer ductility losses owing to the hard, nondeforming SiC second phase. They also are much better in fatigue because the SiC particles or short fibers mitigate the effects of planar slip in precipitation-hardening alloy matrices. Machining, fusion- welding, or cold-forming AMCs is difficult. Mechanical fastening is possible, but drilling fastener holes is difficult and expensive because the wear caused by the hard, reinforcing phases shortens tool life. Most of the AMCs produced to date have used relatively simple Al matrix alloys such as 6061 and 5083. This presumably is because of the conventional wisdom that AMCs are not heat treatable and the perception that no benefit is gained by using more complex alloy matrices. This is probably the case for a conventional solution treat-and-age approach. Consequently, there has been little effort to optimize AMC systems. For the right application where AMCs could provide a significant benefit, this could present an opportunity. For example, using the high-temperature Al-Fe-Co-Ce alloy powder as the matrix could prove interesting and might permit use of AMCs at up to 200 °Celsius-a temperature at which Ti alloys do not provide any significant advantage, but one that is too high for conventional Al alloy~ to be suitable. In sum, while AMCs are not really a commercial materials system today, sufficient research has been performed to establish proof of concept. If an adequate market for AMCs were to emerge, the time and cost to make them commercially available could prove acceptable. Ti Alloys Ti alloys also have been discussed earlier, but mainly in the context of heavy-section, large-load-bearing applications for launch vehicles. Here, the potential of Ti alloys for lighter gauge applications in the warm structure and the TPS is considered. Table 1 shows that at intermediate temperatures, Ti alloys are attractive in all aspects except for specific stiffness. What this table does not capture is Ti alloys' propensity to react with oxygen in the air to form an oxygen-stabilized a. phase layer on the surface known as a case. An example of ex case is shown in Figure 3. 12 UNCLASSIFIED/;Ui9R 8FFl&ia.\k Wli 8NW1.'
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 27 pages are in the text index: search them above, or from the library's search.