Size-dependent plastic deformation characteristics in He-irradiated nanostructured Cu/Mo multilayers: Competition between dislocation-boundary and dislocation-bubble interactions

作者：Zhang, J. Y.; Zeng, F. L.; Wu, K.; Wang, Y. Q.; Liang, X. Q.; Liu, G.^*; Zhang, G. J.; Sun, J.^*

来源：Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 2016, 673: 530-540.

DOI：10.1016/j.msea.2016.06.071

• Cu/Mo multilayers
• He bubbles
• Deformation mechanisms
• Irradiation tolerance
• Size effects

Nanoindentation methodology was used to investigate the plastic deformation characteristics, including the hardness (H), strain rate sensitivity (SRS, m) and activation volume (V*), of Cu/Mo nanostructured metallic multilayers (NMMs) with equal layer thickness (h) spanning from 10 to 200 nm before and after He-implantation at room temperature. Compared with the as-deposited Cu/Mo NMMs, the irradiated Cu/Mo samples exhibited the enhanced hardness particularly at great h, which is caused by the bubble hardening effect. Unlike the as-deposited Cu/Mo NMMs displayed a monotonic increase in SRS (or a monotonic decrease in activation volume) with reducing h, the irradiated Cu/Mo samples manifested an unexpected non-monotonic variation in SRS as well as in activation volume. It was clearly unveiled that the SRS of irradiated Cu/Mo firstly decreased with reducing h down to a critical size of similar to 50 nm and subsequently increased with further reducing h, leaving a minimum value at the critical h. These phenomena are rationalized by considering a competition between dislocation-boundary and dislocation bubble interactions. A thermally activated model based on the depinning process of bowed-out partial dislocations was employed to quantitatively account for the size-dependent SRS of Cu/Mo NMMs before and after irradiation. Our findings not only provide fundamental understanding of the effects of radiation -induced defects on plastic characteristics of NMMs, but also offer guidance for their microstructure sensitive design for performance optimization at extremes.

• 出版日期2016-9-15
• 单位西安交通大学