Wu Wen-Ping, Şopu Daniel, Eckert Jürgen
Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, Wuhan 430072, China.
State Key Laboratory of Water Resources & Hydropower Engineering Science, Wuhan University, Wuhan 430072, China.
Materials (Basel). 2021 May 23;14(11):2756. doi: 10.3390/ma14112756.
Amorphous/crystalline nanolaminate composites have aroused extensive research interest because of their high strength and good plasticity. In this paper, the nanoindentation behavior of CuZr/Cu amorphous/crystalline nanolaminates (ACNLs) is investigated by molecular dynamics (MD) simulation while giving special attention to the plastic processes occurring at the interface. The load-displacement curves of ACNLs reveal small fluctuations associated with shear transformation zone (STZ) activation in the amorphous layer, whereas larger fluctuations associated with dislocations emission occur in the crystalline layer. During loading, local STZ activation occurs and the number of STZs increases as the indentation depth in the amorphous layer increases. These STZs are mostly located around the indenter, which correlates to the high stresses concentrated around the indenter. When the indenter penetrates the crystalline layer, dislocations emit from the interface of amorphous/crystalline, and their number increases with increasing indentation depth. During unloading, the overall number of STZs and dislocations decreases, while other new STZs and dislocations become activated. These results are discussed in terms of stress distribution, residual stresses, indentation rate and indenter radius.
非晶/晶体纳米层状复合材料因其高强度和良好的塑性而引起了广泛的研究兴趣。本文通过分子动力学（MD）模拟研究了CuZr/Cu非晶/晶体纳米层（ACNLs）的纳米压痕行为，同时特别关注界面处发生的塑性过程。ACNLs的载荷-位移曲线显示，非晶层中与剪切转变区（STZ）激活相关的波动较小，而晶体层中与位错发射相关的波动较大。在加载过程中，局部STZ激活发生，并且随着非晶层中压痕深度的增加，STZ的数量增加。这些STZ大多位于压头周围，这与压头周围集中的高应力相关。当压头穿透晶体层时，位错从非晶/晶体界面发射，并且它们的数量随着压痕深度的增加而增加。在卸载过程中，STZ和位错的总数减少，而其他新的STZ和位错被激活。从应力分布、残余应力、压痕速率和压头半径等方面对这些结果进行了讨论。
