Atomistic Simulation of Plastic Deformations in Hydrogen-Saturated Two-Phase Al/θ' Bicrystals

The influence of hydrogen atoms on the deformation behavior of Al/ $$\theta {\kern 1pt} '$$ bicrystals with a (001)Al//(001) $$_{{\theta {\kern 1pt} '}}$$ interphase boundary during shearing has been studied by the molecular-dynamics method. During shearing in the [100]Al direction that is parallel to the (001)Al plane, the initial emission of dislocations from the interphase boundary leads to the development of gliding along the boundary with the formation of a disordered layer of atoms in aluminum. The critical stress of activation of the plastic relaxation reaches 6.4 GPa in this case. With a shear of [100](010)Al, the plastic relaxation occurs due to the generation and gliding of dislocations in aluminum, as well as a plastic flow in a layer of the $$\theta {\kern 1pt} '$$ phase; in this case, plastic relaxation is activated at a shear stress of 7.9 GPa. Introducing hydrogen into the system leads to a decrease in the critical stresses by on average 34% due to a significant decrease in the shear resistance of the $$\theta {\kern 1pt} '$$ -phase material. Systems with hydrogen demonstrated greater sensitivity to a decrease in the straining rate; a 20-fold decrease in the straining rate is accompanied by a 20% decrease in the critical stresses, while for bicrystals without hydrogen, a similar decrease is 5%. A temperature increase leads to a decrease in the critical stresses with an average temperature sensitivity coefficient of –4 MPa/K.