Tensile Deformation of Si Single Crystals with Easy Glide Orientation

Abstract

Silicon single crystals were deformed in tensile tests along the [134] direction between 1173 K and 1373 K. The yield point phenomenon was observed in the specimens deformed below 1273 K, while a continuous yield was observed in the specimens deformed above 1323 K. The values of work-hardening rate in stage II were the same as those reported in other single crystals. Orientation maps of the specimen obtained by using electron backscattered electron diffraction method indicated that stage II starts before the Schmid factor of the secondary slip system became larger than that of the primary slip system. Because of the constraint due to the gripping of the test piece, kink bands are formed during stage I before the onset of stage II, and then the stress state becomes non-uniaxial. This suggests that the formation of kink bands triggers the activation of the secondary, i.e., conjugate slip system to increase the resolved shear stress on the conjugate slip systems.

Fig. 8 (a) Optical micrographs of the gauge sections. (b) Color map using the plots in the inverse pole figure in (c). Arrows indicate kink boundaries. (c) Inverse pole figure with respect to A2. (d) Point-to-origin misorientation measured along a line in (b). (e) Schematic of a dislocation array at kink boundaries.