To understand better the general mechanical behavior of nanotwin boundaries, molecular dynamics simulation studies were used to investigate the responses ofboth nanotwin and nanograin boundaries in copper to stress at the nanoscale, particularly in the critical range of 5–25 nm where the inverse Petch–Hall relation (P–H) may occur in nanocrystalline copper. The obtained results suggest that the twin boundary blocks dislocation movement more effectively and the degree of emitting dislocations under stress was considerably lower than that of grain boundary, leading to superior mechanical behavior. The inverse P–H relation was not applicable to the nanotwinned system. It was also demonstrated that the inverse P–H relation occurring in nanograined materials does not necessarily result from grain boundary sliding.

A Closer Look at the Local Responses of Twin and Grain Boundaries in Cu to Stress at the Nanoscale with Possible Transition from the P–H to the Inverse P–H Relation. L.Yue, H.Zhang, D.Y.Li: Acta Materialia, 2010, 58[7], 2677-84