A comparative study concerning the influence of pre-induced twins and dislocations on the hardening of basal slip and prismatic slip at room
A comparative study concerning the influence of pre-induced twins and dislocations on the hardening of basal slip and prismatic slip at room temperature (RT) and cryogenic temperature (77K) has been performed. One sample without pre-compression (AR sample) and two samples with different strains of pre-compression (PC samples) along the transverse direction (TD) were prepared. The AR and PC samples were tensioned along the rolling direction (RD) and 45°(in the ND-TD plane) direction from ND to activate predominantly prismatic slip and basal slip deformations, respectively. Interestingly, the results demonstrated that the pre-induced {101‾2} twins and dislocations by pre-compression is more effective in strengthening prismatic slip (47–72 MPa increment in yield strength) than basal slip (20-38 MPa increment in yield strength) under cryogenic loading, which is quite different from the hardening tendency observed at room temperature: 18–32 MPa increments of yield strength in prismatic slip-dominated deformation, while 22–42 MPa increments of yield strength in basal slip-dominated deformation. The reversed hardening tendency was understood by quantitative analysis of work hardening by pre-induced twins/dislocations and twin-induced grain refinement. Moreover, the twin-induced grain reorientation effect on the hardening also detailed at 77K and indicates a harder deformation transfer in prismatic slip-dominated deformation than basal slip-dominated deformation.