Effects of Cyclic Loading Performance on Grain Boundary Motion of Nanocrystalline Ni
P Wang and XH Yang and D Peng, METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, 48A, 4977-4989 (2017).
Structural transformations and grain boundary (GB) motion in nanocrystalline Ni under cyclic loading were studied by molecular dynamics simulations, in particular the effects of maximum strain and cyclic strain amplitude. At a fixed cyclic strain amplitude, increases of the maximum strain increased the length of disordered segments at both ends of the GB and removed the GB migration hysteresis. Conversely, the cyclic strain amplitude shows different effects on the GB migration hysteresis at different maximum strains. The nucleation and motion of GB disconnections were not strongly affected by dislocations at a maximum strain of 4 pct. The cyclic strain amplitude slightly influenced GB migration hysteresis, such that the hysteresis was maintained over six cycles. Nevertheless, at a maximum strain of 6 pct, disordered GB segments at both ends of the GB shortened the distance between the two pinning points of GB motion. Thus, the cyclic strain amplitude has a marked effect on the GB migration hysteresis.
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