Shen Jinchuan, Zhou Jinjie, Zhao Gang, Gong Caiyun, Yu Jingui, Xia Zhaohui, Xian Fankai
School of Mechanical Engineering, North University of China Taiyuan 030051 P. R. China
Hubei Key Laboratory of Mechanical Transmission and Manufacturing Engineering, Wuhan University of Science and Technology Wuhan 430081 P. R. China.
RSC Adv. 2022 Aug 1;12(33):21235-21246. doi: 10.1039/d2ra03051a. eCollection 2022 Jul 21.
Temperature has a great influence on the mechanical properties of nano-materials. The molecular dynamics method was used to study the effect of temperature on the tension-compression asymmetry and Bauschinger effect of nano single crystal aluminum (NSCA). The strain-hardening behavior of NSCA in the tensile plastic stage is significantly enhanced when the temperature is higher than 400 K. The plastic deformation mechanism of tensile loading shifts from slip blocking of dislocations in grains to dislocation nucleation. The degradation of the mechanical properties of NSCA under compressive loading increases gradually with the increase of temperature. Dislocation emission is limited under compressive loading. Nonetheless, plastic deformation may still be regulated by dislocation slip during severe plastic deformation stages and at elevated temperatures. Temperature enhancement can effectively promote the movement of pre-dislocations and eliminate residual stresses. A new microscopic insight into the temperature attenuated Bauschinger effect is provided. This study provides important theoretical guidance for a comprehensive and in-depth understanding of the high-temperature mechanical properties and microstructure evolution mechanism of NSCA.
温度对纳米材料的力学性能有很大影响。采用分子动力学方法研究了温度对纳米单晶铝（NSCA）拉伸-压缩不对称性和包申格效应的影响。当温度高于400 K时，NSCA在拉伸塑性阶段的应变硬化行为显著增强。拉伸加载时的塑性变形机制从晶粒内位错的滑移阻碍转变为位错形核。NSCA在压缩加载下的力学性能退化随温度升高而逐渐增加。压缩加载下位错发射受到限制。尽管如此，在严重塑性变形阶段和高温下，塑性变形仍可能由位错滑移来调节。温度升高可有效促进预存位错的运动并消除残余应力。提供了对温度减弱的包申格效应的新微观见解。该研究为全面深入理解NSCA的高温力学性能和微观结构演化机制提供了重要的理论指导。
