Mechanism of Deformation of Al Single Crystals Foils under Restricted Cyclic Tension Conditions

摘要

Structure formation during plastic deformation is well known to have many distinctions under restricted conditions in comparison with "free" conditions. For investigation of these processes we have selected: (a) materials with highly pronounced features of structure formation, i.e. single crystal plates (thick plates) glued to specimens; (b) the simple scheme of loading that allows us to observe the repeatable and stable appearance of these features, i.e. restricted cyclic tension of the plates caused by unidirectional cyclic tension of the specimens; (c) easy non-destructive methods of "online" observation of the features, i.e. optical microscope with CCD-camera connected to computer. The high pure single crystals plates (99.995 wt.%Al, orientation {100}<100>, thickness 0.2 mm, length 30 mm and width 10 mm) were polished electrically for obtaining glassy smooth surface and reliably glued to flat surface of Al-alloy specimens near weld zone. Then specimen-plate pairs were tested on hydropulse machine at room temperature with a saw-like loading cycle was minimal stress near zero and maximal one in the range 140-250 MPa, where specimen was deformed always elastically regime and plate ― plastically.