A molecular dynamics study on tensile and low cycle fatigue behaviors of Ti single crystal nanowire

Abstract It is essential to reveal the fatigue mechanism of the main elements in alloys at the nano scale for the material design against fatigue failure. In the present study, molecular dynamics (MD) simulations have been employed to investigate the static tensile and low cycle fatigue (LCF) behaviors of a defect free single crystal Ti nanowire with hexagonal close-packed (HCP) structure at room temperature (300 K). Results showed that the explosive initiations of body centered cubic and disordered atoms led yielding of Ti nanowire under static tensile load. The following stress response to constant amplitude cyclic strain was found strongly relatived to the instantaneous microstructure configuration at the first unloading. Variation of potential energy was used to characterize the competitions between face-centered cubic (FCC) atoms, body-centered cubic (BCC) atoms and disordered atoms. A conclusion was drew that the cyclic characteristics of Ti nanowire were heavily dependent on the dominant atom configuation during the fatigue process. Additionally, this research also found that static tensile yield strength of Ti nanowire may vary notably with respect to crystal direction, e.g. for [ 1 ¯ 100] (or for [0001]) it is about 1.5 times of that for [11 2 ¯ 0].