Tech Briefs

Super-High-Strength Aluminum Alloy

The project team achieved the desired properties with half-sized, subscale preforms. The aluminum alloy is 38% lighter weight, significantly less expensive, and more resistant to hydrogen embrittlement than the titanium alloys currently used in liquidfueled rocket engine turbopumps. The team has succeeded in efforts to cast the aluminum alloy in bars 76 mm in diameter and 6 m in length. Once the researchers are able to demonstrate fullscale castings with no appreciable material property changes, the alloy will be appropriate for additional applications, and the Air Force, DoD, and aerospace industry will begin to benefit from its accompanying cost reductions and streamlined manufacturing processes.

The project team successfully developed a high-strength aluminum alloy in both cast and wrought forms, both of which exhibit higher specific strength and the same ductility as the titanium alloy used in cryogenic turbopumps. During follow-on testing, scientists will produce larger cast billets and forgings in order to verify the results. They will also complete certification of the forging preforms to determine tensile properties, notch sensitivity, fracture toughness, and high-cycle fatigue response. Finally, they will conduct additional fluidity and tensile property testing to prove the casting ability of the selected alloy. Scientists plan to conduct follow-on IHPRPT efforts to determine whether the super-highstrength aluminum alloy may have a broader impact on aerospace applications.

Dr. Oleg N. Senkov (UES, Inc.), Dr. Daniel B. Miracle, and Mr. Timothy R. Anderl (Anteon Corporation), of the Air Force Research Laboratory’s Materials and Manufacturing Directorate, wrote this article. For more information, contact TECH CONNECT at (800) 203-6451 or place a request at http://www.afrl.af.mil/techconn_index.asp. Reference document ML-H-05-41.