Advanced Aluminum Materials for Rocket Turbopump Rotors

The objective of the Phase II program is to continue development of a super-high strength cast and wrought aluminum alloy for a liquid hydrogen turbopump impeller. In Phase I, significant improvement in strength of a 7050 aluminum alloy by modifications ofchemistry and thermomechanical/heat treatment processes was demonstrated. The modified alloy showed very high strength of 850 MPa and elongation of 8% at 77K. Even much higher strength of 1060 MPa was achieved after certain heat treatment, at elongation ofabout 1%. Phase II will pursue (a) optimization of the alloy composition, (b) development of industry-compatible thermomechanical and heat treatment processes for this alloy, and (c) sufficient characterization of sub-scale components to permit preliminarydesign of a real-scale turbopump impeller. Integral to this advanced development is a comprehensive understanding of the microstructure and physical metallurgy of the modified alloy in controlling the desired properties to direct further development andcommercialization. Mechanical property data on the major design driver properties will be determined, both at room and cryogenic temperatures. It is believed that the Phase II effort will bring the alloy to a commercially usable state, and a full-scalecomponent produced from this alloy in the following Phase III will perform as predicted and required.