TY - JOUR

T1 - Grain boundary structure and deformation defects in nanostructured Al-Mg alloys processed by high pressure torsion

AU - Man, Ping Liu

AU - Roven, Hans J.

AU - Ungár, Tamas

AU - Balogh, Levente

AU - Murashkin, Maxim

AU - Valiev, Ruslan Z.

PY - 2008/1/1

Y1 - 2008/1/1

N2 - An Al-0.5 Mg alloy and a commercial AA5182 alloy were subjected to high pressure torsion (HPT) to five turns under pressure of 6 GPa at room temperature. The grain boundary structure and deformation defects were investigated after HPT using high-resolution transmission electron microscopy (HRTEM). Low-angle, high-angle, equilibrium and non-equilibrium grain/subgrain boundaries, twin boundaries, full dislocations, dipoles, microtwins and stacking faults were identified by HRTEM. Extrinsic 60° dislocations in the form of dipoles were frequently observed in non-equilibrium grain/subgrain boundaries. In addition subgrain size distributions and dislocation densities were quantified by x-ray line profile analysis. It was observed that the average grain size decreased from about 120 nm to 55 nm as the Mg content increased from 0.5 to 4.1 wt%. Concomitantly the average stored dislocation density increased from 1.7 to 12.8 × 1014 m-2. Based on the HRTEM investigations and the x-ray line profile analyses, the deformation mechanism associated with the typical grain boundaries and deformation defects in the aluminium alloys were discussed.

AB - An Al-0.5 Mg alloy and a commercial AA5182 alloy were subjected to high pressure torsion (HPT) to five turns under pressure of 6 GPa at room temperature. The grain boundary structure and deformation defects were investigated after HPT using high-resolution transmission electron microscopy (HRTEM). Low-angle, high-angle, equilibrium and non-equilibrium grain/subgrain boundaries, twin boundaries, full dislocations, dipoles, microtwins and stacking faults were identified by HRTEM. Extrinsic 60° dislocations in the form of dipoles were frequently observed in non-equilibrium grain/subgrain boundaries. In addition subgrain size distributions and dislocation densities were quantified by x-ray line profile analysis. It was observed that the average grain size decreased from about 120 nm to 55 nm as the Mg content increased from 0.5 to 4.1 wt%. Concomitantly the average stored dislocation density increased from 1.7 to 12.8 × 1014 m-2. Based on the HRTEM investigations and the x-ray line profile analyses, the deformation mechanism associated with the typical grain boundaries and deformation defects in the aluminium alloys were discussed.

KW - Aluminium alloys

KW - Deformation defects

KW - Grain boundary structure

KW - High pressure torsion

KW - Non-equilibrium grain boundaries

KW - Severe plastic deformation

UR - http://www.scopus.com/inward/record.url?scp=56349172233&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:56349172233

VL - 584-586 PART 1

SP - 528

EP - 534

JO - Materials Science Forum

JF - Materials Science Forum

SN - 0255-5476

ER -