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Significant corrosion resistance improvement was achieved in solid-solution treated(T4) Al-Cu alloy after severe grain refinement through equal-channel angular pressing.The bulk ultrafine-grained Al-Cu alloy with grain sizes of 200-300 nm has higher pitting potential(elevated by about 34 mV,SCE) and lower corrosion current density(decreased by about 3.88μA/cm~2) in polarization tests than the as-T4 alloy,and increased polarization resistance(increased by about 5.7 kΩ·cm~2) in electrochemical impendence spectrum tests,along with alleviated corrosion damage in immersion tests.Two factors responds to the improved corrosion resistance of the alloy:the first is the refinement of residualθ-phase(Al_2Cu) particles leading to the lower micro-galvanic currents and reduced susceptibilities to pitting corrosion,the second is the mass of strain-induced crystalline defects providing more nucleation sites for the formation of more volume fractions of stable oxide film.
Significant corrosion resistance improvement was achieved in solid-solution treated (T4) Al-Cu alloy after severe grain refinement through equal-channel angular pressing. The bulk ultrafine-grained Al-Cu alloy with grain sizes of 200-300 nm has higher pitting potential (elevated by about 34 mV, SCE) and lower corrosion current density (decreased by about 3.88 μA / cm ~ 2) in polarization tests than the as-T4 alloy, and increased polarization resistance (increased by about 5.7 kΩ · cm ~ 2) in electrochemical impendence spectrum tests, along with alleviated corrosion damage in immersion tests. Two factors responds to the improved corrosion resistance of the alloy: the first is the refinement of residual θ-phase (Al_2Cu) particles leading to the lower micro-galvanic currents and reduced susceptibilities to pitting corrosion, the second is the mass of strain-induced crystalline defects providing more nucleation sites for the formation of more volume fractions of stable oxide film.