A Study on the Combined Treatment of Cryorolling, Short-Annealing, and Aging for the Development of Ultrafine-Grained Al

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THE most important mechanical properties for any materials selected for structural applications are strength and ductility. However, they are often mutually competitive, that is, a material may be either strong or ductile but rarely both at the same time.[1] A similar behavior is observed in bulk ultrafine-grained (UFG) materials[2–5] in which the materials exhibit a high strength but a low ductility. This low ductility is attributed to insufficient strain hardening because of an inability to accumulate dislocations in the materials.[5–7] The low ductility of UFG has limited their practical application significantly, and therefore, the strategies to improve their poor ductility are being given due importance by several researchers.[8–15] However, earlier approaches have improved the ductility of the materials by sacrificing its yield strength. In recent years, numerous research activities are being pursued to improve the strength and ductility simultaneously of severely deformed precipitation-hardenable Al alloys. Recently, equal-channel angular pressing (ECAP) has been applied to different Al alloy systems to obtain high SUSHANTA KUMAR PANIGRAHI, Research Associate, and R. JAYAGANTHAN, Associate Professor, are with the Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee 247667, India. Contact e-mail: [email protected] Manuscript submitted January 31, 2010. Article published online June 22, 2010 METALLURGICAL AND MATERIALS TRANSACTIONS A

strength and ductility.[16–20] Horita et al.[16] studied the effect of post-ECAP low-temperature aging on the tensile behavior of an Al 10.8 wt pct Ag alloy. They reported, based on high-resolution transmission electron microscopy (HRTEM) investigations, that work hardening can be improved by producing fine ‘‘g-zone’’ precipitate particles with sizes