AAWSAP DIRD, Materials for Advanced Aerospace Platforms, January 2010

This Defense Intelligence Reference Document, DIA-08-0912-008, is dated 12 January 2010. It was prepared by the Defense Warning Office's Acquisition Support Division at the Defense Intelligence Agency as one of a series of FY 2009 technology reports under the Advanced Aerospace Weapon System Applications 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, and titanium aluminides. It concludes that newer materials and integrated design could improve on the space shuttle.

From the source: Release of 2026-09-18 Incident: 1/12/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys the structural materials needed for advanced aerospace platforms and argues that material choice cannot be separated from overall vehicle design, because launch vehicles, space vehicles, reusable systems, and propulsion hardware each face different temperature, durability, weight, and manufacturing constraints. The report reviews a range of candidate material classes, including advanced aluminum alloys; polymer-, aluminum-, and titanium-matrix composites; titanium alloys; nickel-base alloys; refractory metals; ceramic-matrix composites; carbon-carbon composites; and titanium aluminides. It emphasizes that balancing performance against practical limits such as fabrication methods, cost, inspection, contamination control, and service environment remains a major challenge. Its overall conclusion is that many promising materials exist, but their usefulness depends on application-specific tradeoffs and on closer integration of material selection with design and manufacturing, with some systems judged to be more valuable targets for development than others.

UNCLASSIFIED/;'FOR OFFl&IAl W&IE 9fslllf
Figure 3. Micrograph Showing a Phase Formation at the Surface of a Ti Alloy
That has Been Exposed to Air at Elevated Temperature
The a case is harder than the matrix because oxygen is a potent a-phase solid-solution
strengthener. As with almost all other strengthening reactions, the increased strength is
accompanied by reduced ductility. Again, drawing on conventional wisdom, the
presence of a case in sheet structures has been forbidden by specification, design
practice, or whatever means a company uses to manage its hardware. Less clear is how
truly detrimental a case is to properties. Essentially no effort has been made to
determine whether it can be tolerated if the affected hardware is allowed to operate at
a modestly reduced stress. The industry standard for a case has essentially been one of
zero tolerance. Given the significant potential weight advantage associated with use of
Ti alloys in portions of the TPS and warm structure, this conservative approach needs to
be revisited. Several key questions related to this are:
• Is a case truly detrimental to the load-bearing capability of Ti alloy sheet structures?
• If so, is there a limiting amount that can be tolerated without significantly degrading
the structural capability?
• Which properties are the most severely degraded?
• Are a case formation and property degradation alloy dependent?
• If so, which alloys are the most tolerant of a case formation?
13
UNCLASSIFIED/ /FOR OFFI&IAl Wliliii QfslL¥