Atomistic modeling of strain-controlled cyclic loading in TiAl crystalline nanowire

In this paper, atomistic modeling of L10-TiAl nanowire has been performed utilizing the Embedded Atom Method (EAM) potential under strain-controlled cyclic loading. A nanowire oriented along the <100> axis with a cross-sectional dimension (D) of ~80 Å with a Length-to-width (L/D) ratio of 10.0 has been considered. Strain-controlled cyclic loading at room temperature has been performed by oscillating the nanowire length dimension sinusoidal with a specific amplitude and period. Tension-compression cyclic loading was employed with zero mean strain. Cyclic loading with percentage strains (%ε) of one to five percent have been considered. It has been observed that the cyclic stress in the nanowire continues to fluctuate during the initial loading cycles. However, once the nanowire becomes stable, a smooth variation of stresses with varying strain has been observed. The cause of initial fluctuations in the nanowire has been studied by varying (a) the amount of load (strain) applied, (b) the nanowire structure during cyclic loading, and (c) the rate at which the load has been applied. It has been identified that the rate of loading could be used for controlling the initial fluctuations of nanowire. Finally, a method for the calculation of cyclic stress versus cyclic strain for nanowires has been proposed. A cyclic stress versus cyclic strain curve has been plotted for a given L/D = 10 and a period of 10 ps. Results show that the TiAl nanowire is having 3/2 times higher stiffness in tension as compared to compression at a given strain under cyclic loading.