Size-dependent of compression yield strength and deformation mechanism in titanium single-crystal nanopillars orientated [0001] and [112̄0]

Different size effects and deformation mechanisms are revealed in α-titanium (Ti) single crystal nanopillars orientated for [112̄0] and [0001] based on molecular dynamics simulations. The strength-size relationship changes from “smaller is stronger” to “smaller is much weaker” when the width of nanopillars reduces from 19 nm to 3 nm. The “smaller is much weaker” is attributed to that the surface effect caused by a thermal vibration of surface atoms leads to the initiation and growth of surface dislocations.