Segmentation during Processing of Bulk Nanostructures by Equal Channel Angular Pressing

Severe plastic deformation (SPD) has attracted researchers’ attention during last decade and there is an ever going interest in SPD methods to process bulk ultra-fine grained (UFG) and nanostructures (NC) materials. Equal channel angular pressing (ECAP) has attracted more attention than other SPD methods in the last decade due to Easy configuration, low cost and the ability to produce relatively large samples of UFG and NC materials in the industrial scale. It is known that ECAP processing may introduce significant damage, in the form of shear bands, cracking, and segmentation, into the processed material. This research provides experimental evidence for the occurrence of cracks and segmentation. ECAP procedure was conducted on the four commercial Cu-based alloys in room temperature (RT) and ۳۵۰°C. In order to investigate of the hardnessimpact on the segmentation, microhardness test was utilized. Results demonstrated that although there are many parameters involved in the segmentation, there is direct relation between the segmentation and hardness so that by decreasing the hardness value from ۱۴۷ HV to ۸۶ HV, the cracking and segmentation during ECAP becomes lighter and smaller until it can be disappeared finally. Absence of segmentation is very important in ECAP because the segmented samples are not useable in the industrial applications.

کلیدواژه ها:

severe plastic deformation ، ECAP ، segmentation ، microhardness ، cu-based alloys