Computational Design of High-Strength Anodize-Free Stainless Aluminum Alloys for Aerospace Applications

Most aerospace aluminum alloys are anodized in order to enhance corrosion resistance. Unfortunately, anodization can reduce fatigue strength by as much as 40%, and also results in a hazardous materials waste-stream. Under this proposed SBIR program, QuesTek Innovations LLC, a leader in the field of computational materials design, will develop a new high-strength anodize-free stainless aluminum alloy with intrinsic corrosion behavior similar to anodized 7xxx alloys and mechanical properties equivalent to non-anodized 7075-T6 alloy. General corrosion is largely driven by differences in electrochemical behavior between the different phases in the system, and QuesTek will utilize a microstructural concept of combining precipitates and constituents with a matrix having similar electrochemical potential, in order to eliminate localized general corrosion. The electrochemical design framework will use QuesTek’s state-of-the-art computational design tools for aluminum alloys, including custom thermodynamic and kinetic databases, microstructural evolution models, physics-based strength models, solidification process simulations, and stress-corrosion cracking models. In the program QuesTek will partner with OEMs who will help define the material and process requirement matrix, and ultimately lead the alloy implementation. Concept feasibility will be demonstrated on model alloys fabricated in the Phase I program. Production-scale fabrication of the designed alloy will be demonstrated in Phase II.