Relation between microstructural features and mechanical properties in oxygen free high conductivity copper after Equal-Channel Angular Pressing

Abstract

An oxygen free high conductivity (OFHC) copper was subjected to maximum 13 ECAP passes to achieve a sufficiently high degree of deformation. Strength properties (yield stress and ultimate tensile strength) show obvious increase up to the 4 th pass. In the 6 th ECAP pass, the yield stress and ultimate tensile strength are stabilized at a maximum of 449 MPa. Microstructure studies showed that the 1 st ECAP pass caused a significant increase of dislocation density. These dislocations are arranged in cells, forming dense dislocation walls at low-angle subgrains. After the 5 th ECAP pass, well-defined equiaxed ultrafine grains of diameter approximately 500 nm had emerged forming high-angle grain boundaries. The defect density studies carried out by positron annihilation spectroscopy method revealed an increase in a defect density (vacancies, dislocations) up to the 4 th pass, consequently with number of ECAP passes increasing, decrease in defects density (seen by positrons) was observed.K e y w o r d s : dislocation, grain boundaries, equiaxed ultrafine grained microstructure, electron microscopy, Equal Channel Angular Pressing (ECAP)

The Effect of Severe Plastic Deformation and Heat Treatment on CuCrZr Alloys

“…Severe plastic deformation (SPD) methods applied to metals enable specific microstructural and substructural features to be formed during the processing resulting in an unexpected combination of mechanical properties [2,3]. Formation of such structures in materials causes microstructural refinement to the ultrafine-grained (UFG) or even nanocrystalline (NC) area [4][5][6].…”

“…ECAP has been successfully used over the last decade to insure the ultrafine-grained structures in a wide range of ductile metals including pure Cu and Cu alloys [4,5,[10][11][12][13]. Microstructure is refined to equiaxed subgrains/grains below 1 µm under high strains through simple shear, accompanied with a significant increase of strength.…”

“…Microstructure is refined to equiaxed subgrains/grains below 1 µm under high strains through simple shear, accompanied with a significant increase of strength. During ECAP processing, boundaries with relatively low misorientation are formed by dislocations rearrangement at lower strain (dislocation cells substructure), which are progressively transformed to higher angle grain boundaries at higher strains [5,14,15]. At the * corresponding author; e-mail: andrea.kovacova@tuke.sk same time ductility remains good for such heavily deformed Cu alloys [16].…”

Microstructural evolution and mechanical properties of low SFE Cu-Al alloys processed by cryorolling followed by short-annealing

“…3g) also confirmed that the recrystallization and grain growth mechanisms were prevalent at a temperature of 300°C. [45][46][47] explained that the dimple size of the UFG oxygen free high conductivity copper gradually decreases with increase in the strain rate. This is due to the increase in the brittleness with increase in the strain rate.…”

Bulletin of the Polish Academy of Sciences: Technical Sciences

“…The application of the severe plastic deformation (SPD) method in metals and metal alloys that have specific microstructural and design features may lead to high mechanical properties [2,3]. It is related to the strong refinement of the microstructure to the ultrafine-grained (UFG) or nanocrystalline (NC) level [4][5][6].…”