Microstructure and strength of severely deformed fcc metals

The relationship is examined between the microstructure and the strength of ultrafine-grained fcc metals (Al, Al-Mg alloys, Cu and Ni) processed by severe plastic deformation. The saturation value of the yield strength obtained at high strains is correlated with the dislocation density by using the Taylor equation. The results suggest that the main strengthening mechanism in severely deformed fcc metals is the interaction between dislocations. Furthermore, the saturation strength of different fcc metals deformed at room temperature may be described by using the shear modulus and the absolute melting point. The results of the analysis show that for Al-Mg alloys the addition of the Mg alloying element to the Al matrix leads to an increase in the maximum value of the dislocation density and consequently to an increase in the strength. (C) 2006 Elsevier B.V. All rights reserved.