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

PA Bezborodova and VS Krasnikov and AE Mayer, PHYSICS OF METALS AND METALLOGRAPHY, 124, 857-869 (2023).

DOI: 10.1134/S0031918X23601580

The influence of hydrogen atoms on the deformation behavior of Al/theta ' bicrystals with a (001)(Al)//(001)(theta)' 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 ' 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 '-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.

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