Twinning and dislocation activity in silver processed by severe plastic deformation
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Severe plastic deformation (SPD) provides attractive procedures for producing ultrafine-grained (UFG) metals in bulk form [1, 2]. One of the most frequently used methods is equal-channel angular pressing (ECAP) where it is possible to produce relatively large bulk UFG metals having dimensions of several centimeters in all directions . It is now well established that the high strength of metals processed by ECAP is due to their high dislocation densities and small grain sizes . There have been extensive reports documenting the evolution of the microstructure during the processing by ECAP of pure face-centered cubic (fcc) metals having medium or high stacking fault energies (SFE). Thus, it was reported that in metals such as Al and Cu, the grain size reaches a minimum value and the dislocation density saturates after about 4 passes of ECAP . Nevertheless, very little information is available at present describing microstructural evolution during ECAP in pure fcc...
KeywordsDislocation Density Stack Fault Energy Etching Rate Lattice Dislocation Twin Density
This work was supported in part by the Hungarian Scientific Research Fund, OTKA, Grant Nos. K67692 and K71594 (JG and NQC) and in part by the National Science Foundation of the United States under Grant No. DMR-0243331 (TGL). In addition, JG is grateful for the support of a Bolyai János Research Scholarship of the Hungarian Academy of Sciences and NQC thanks the Hungarian-American Enterprise Scholarship Fund for support. The authors thank Andrea Jakab for the preparation of the TEM samples and JG is grateful to Prof. Geza Tichy for helpful discussions.
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