Wang Luling, Cao Yang, Zhao Yonghao
Nano and Heterogeneous Materials Center, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, People's Republic of China.
School of Materials Science and Engineering, Hohai University, Changzhou 213200, People's Republic of China.
Nano Lett. 2024 Jul 24;24(29):9004-9010. doi: 10.1021/acs.nanolett.4c02086. Epub 2024 Jul 12.
Multiprincipal element alloys usually exhibit earlier pop-in events than pure metals and dilute solid solutions during nanoindentation experiments. To understand the origin of this phenomenon, large-scale atomic simulations of nanoindentation were performed on a series of metallic materials to investigate the underlying physics of incipient plasticity at the nanoscale. Statistical result shows that lattice distortion δ and normalized critical pressure / follow a power-law relationship. Via quantitative analysis on the relative positions of the atoms within the nearest neighbor shell, the physical origin of premature incipient plasticity is revealed as severe lattice distortion induces large relative atomic displacement, so only a small indentation strain is required to meet the critical displacement threshold that triggers incipient plasticity. Therefore, for perfect crystals, lattice distortion is an intrinsic and determinative factor that affects the first pop-in event.
在纳米压痕实验中，多主元合金通常比纯金属和稀固溶体表现出更早的压入事件。为了理解这一现象的起源，对一系列金属材料进行了纳米压痕的大规模原子模拟，以研究纳米尺度下初始塑性的潜在物理机制。统计结果表明，晶格畸变δ和归一化临界压力/遵循幂律关系。通过对最近邻壳层内原子相对位置的定量分析，揭示了过早初始塑性的物理起源，即严重的晶格畸变会引起较大的相对原子位移，因此只需要很小的压痕应变就能达到触发初始塑性的临界位移阈值。因此，对于完美晶体，晶格畸变是影响首次压入事件的一个内在且决定性的因素。
