Introduction: High-energy ball milled (HEBM) alloys exhibit superior strength and corrosion resistance [1–5] to commercial alloys. This improvement in properties is attributed to the combined effect of suitable alloying elements in super-saturated solid solution, nano-sized grains and fine uniformly distributed secondary phases [6–8]. These microstructural features exist in a metastable state, therefore, providing enough thermal energy will promote the formation of equilibrium phases inverting the benefits of the nanostructured alloy . Formation of coarse intermetallics lessens corrosion resistance by promoting micro-galvanic interactions whilst providing small strength benefit. Additionally, as the solute in the matrix depletes the difference in electrochemical potential becomes larger, which further deteriorates its resistance to localized corrosion. Moreover, impairments in strength can also result from exposure to high temperatures by recrystallization, grain growth and relieved internal stress.
Authors: J. Esquivel, T. Larimian, T. Borkar, and R. K. Gupta