Room-temperature deformation of single crystals of WC investigated by micropillar compression

The room temperature deformation behavior of single crystals of WC has been investigated as a function of crystal orientation and specimen size by micropillar compression tests. Plastic flow is successfully observed at room temperature by the operation of slip on {01 (1) over bar0} < 2 (11) over bar3 > when the specimen size is reduced to micrometer orders. This slip system is the only operative slip system in WC at room temperature, and thus plastic flow is not observed for crystal orientations close to the c-axis orientation. The bulk critical resolve shear stress (CRSS) is estimated to be 1.2 +/- 0.3 GPa from the extrapolation of the size-dependent CRSS. The 1/3 < 2 (11) over bar3 > dislocation carrying slip on {01 (1) over bar0} dissociates into two identical collinear partial dislocations separated by a stacking fault with the energy of 211 similar to 264 mJ/m(2). The preference of slip along < 2 (11) over bar3 > among possible directions (such as < 2 (11) over bar0 > and [0001]) on the {01 (1) over bar0} prism plane is discussed in terms of dislocation self-energy based on anisotropic elasticity, stacking fault energy, dislocation dissociation and Peierls stress for dislocation motion. The lowest Peierls stress arising from the shorter Burgers vector (1/6 < 2 (11) over bar3 >) of dislocations as a result of collinear dissociation of dislocations with b = 1/3 < 2 (11) over bar3 > on the {01 (1) over bar0} slip plane is considered to be the main reason for the preference of the {01 (1) over bar0} < 2 (11) over bar3 > slip system.

Automated summary

The room temperature deformation behavior of single crystals of WC has been investigated by micropillar compression tests. The results show that plastic flow is observed when the specimen size is reduced to micrometer orders and the crystal orientation is not close to the c-axis orientation. The preference of <2 (11) over bar3> slip system on {01 (1) over bar0} prism plane is explained by considering factors such as dislocation self-energy and Peierls stress.