Molecular Dynamics Simulations of Nanoindentation of CuNi Alloy

Abstract

In this paper, molecular dynamics was used to simulate the indentation process of copper–nickel (CuNi) alloy. Its mechanical properties and behaviors were investigated focusing on factors such as indentation velocity, test temperature and crystal orientation. Generally speaking, dislocation generations and slips, stacking faults, extended dislocations and deformation twins, one or more of them come into play the dominant role during plastic deformation, which in return leads to an improved or reduced hardness of CuNi alloy. Specifically, simulations and analyses reveal the following: (1) its hardness [Formula: see text] increases with [Formula: see text] increasing, but the reduced elastic modulus [Formula: see text] is not sensitive to [Formula: see text]; when it comes to test temperature [Formula: see text], both [Formula: see text] and [Formula: see text] are reduced at elevated [Formula: see text]; besides, the CuNi alloy along [Formula: see text] owns the highest [Formula: see text] and [Formula: see text], the value of [Formula: see text] along [Formula: see text] is slightly smaller than that along [Formula: see text] (2) the dislocation density [Formula: see text] varies severely in the early stage of indentation and then generally levels off when indentation depth reaches approximately 1.5[Formula: see text]nm; by and large, its hardness and dislocation density follow the classical Taylor hardening model and the hardening coefficient does depend on the three factors; (3) the plastic-zone size parameter [Formula: see text], when [Formula: see text] or equivalently [Formula: see text] can be taken as constant roughly 4.0 except in the case of indentation along [Formula: see text], in which it is about 5.7.