Titanium alloys are attractive as structural materials mainly due to their high specific strength and excellent corrosion resistance. Modifying conventional Ti alloys to impart nanostructural features holds promise for improving specific strength without reducing corrosion resistance. This study aimed to evaluate the corrosion behavior of a nano/sub-micron F401 titanium alloy compared to its conventional Ti-6Al-4V counterpart. Following mechanical alloying and extrusion, the microstructure was evaluated using optical microscopy, SEM, HRSEM, and X-ray diffraction analysis. Mechanical properties were evaluated by tension and micro-hardness tests. The corrosion behavior was examined by an immersion test, salt spray testing, and potentiodynamic polarization analysis. Stress corrosion resistance was evaluated by slow strain rate testing (SSRT) in terms of UTS and time to failure versus strain rate. All the corrosion tests were carried out in 3.5% NaCl solution apart from the salt spray testing, which was done in 5% NaCl solution. The results indicate that the corrosion resistance of the novel F401 alloy was not different from its Ti-6Al-4V counterpart, although the mechanical strength was improved. Thus, the grain refinement in the F401 alloy increased the mechanical strength, whereas neither the grain refinement nor the porosity acquired during the preparation process impaired the excellent corrosion resistance.

A systematic study was carried out to evaluate the corrosion performance and stress corrosion resistance of E950 aluminum alloy with nano/sub-micron structure in 3.5% NaCl solution. The conventional coarse-grained counter-part alloy used as a reference alloy was obtained by remelting and extrusion of an alloy with the same composition as the E950 alloy (Al -4.65%Mg). Microstructure examination was carried out using SEM, HRSEM, and X-ray diffraction analysis, while the corrosion behavior was evaluated using immersion test, salt spray testing, and potentiodynamic polarization analysis. The stress corrosion resistance was evaluated using Slow Strain Rate Testing (SSRT) tests in 3.5%NaCl solution. The results obtained indicated that the corrosion and stress corrosion resistance of E950 alloy were relatively reduced compared to that of the conventional coarse-grained alloy. In particular, the inherently improved Ultimate Tensile Strength of E950 alloy was significantly decreased under stress corrosion condition in 3.5% NaCl solution, especially with a low strain rate (2.5 Â 10 À8