Innovative Approaches to the Development of Corrosion Resistant Aircraft Alloys

Aluminum alloys are known to suffer from Stress Corrosion Cracking(SCC). SCC of high strength alloys can proceed rapidly, and can lead to devastating structural failures. However, a solid understanding of combined interactions of metallurgical, environmental and mechanical factors surrounding the crack tip during SCC is still elusive. Therefore, Al alloy developement for high corrosion resistance has been empirical in nature. The objective of this study is to understand the effect of microstructure in conjuction with the local environment(chemical and electrochemical)on the transition behavior from the incubation regime to high rate crack propagation regime during SCC. A quantitative predictive model will be developed based on the mechanistic underestanding fo SCC. This model will be utilzed in development of a new Al alloy most suitable for Navy aircrafts which normally operates in the most severe environment.