Molecular Dynamics Simulations of Nanoindentation of CuNi Alloy

B Han and C Zhang and MX Shi, INTERNATIONAL JOURNAL OF APPLIED MECHANICS, 14, 2250011 (2022).

DOI: 10.1142/S1758825122500119

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 H increases with v(ind) increasing, but the reduced elastic modulus E-r is not sensitive to v(ind); when it comes to test temperature T, both H and E-r are reduced at elevated T; besides, the CuNi alloy along 111 owns the highest H and E-r, the value of H along 001 is slightly smaller than that along 110; (2) the dislocation density rho varies severely in the early stage of indentation and then generally levels off when indentation depth reaches approximately 1.5 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 f, when h/a(c) approximate to 0.6 or equivalently h/R approximate to 0.53 can be taken as constant roughly 4.0 except in the case of indentation along 111, in which it is about 5.7.

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