Thickness‐Dependent Tensile and Fatigue Behavior of A Single‐Slip‐Oriented Cu Single Crystal

• Published in: Crystal research and technology (1979) 2017-12, Vol.52 (12), p.n/a
• Main Authors: Liu, Ming‐Qiu, Liu, Ya‐Lan, Yan, Ying, Han, Dong, Li, Xiao‐Wu
• Format: Article
• Language: English
• Subjects: copper single crystal; dislocation structure; fatigue; fracture; size effect; tension
• ISSN: 0232-1300; 1521-4079
• DOI: 10.1002/crat.201700178

To explore the micro‐mechanism for the size effect of the mechanical behavior of metallic crystals, the tensile and fatigue behavior of [3¯45] Cu single crystal with t of 0.1−2.0 mm is investigated. The results show that with the reduction of t, an obvious increase in σYS and a slight decrease in σUTS take place; meanwhile, the δ evidently reduces, especially as t < 0.6 mm, while the Nf first sharply increases and then decreases at a constant stress amplitude of 80 MPa. The activated slip system reduces with t under tensile loading, and the fracture modes are transferred from ductile to slip separation rupture, whereas under cyclic loading, slip separation rupture becomes dominant especially at t = 2.0 and 0.1 mm. Correspondingly, the tensile microstructures are transformed from the cell‐walls to dislocation cells, while dislocation cells are the dominant microstructure in fatigued specimens, and the dislocation density obviously decreases with decreasing t. In a word, a strong dependence of tensile and fatigue behavior on t is exhibited for the [3¯45] Cu single crystal. The specimen thickness (t = 0.1−2.0 mm) effect on the tensile and fatigue behavior of a single‐slip‐oriented Cu single crystal is investigated. With the reduction of t, an obvious increase in σYS and a slight decrease in σUTS occur; meanwhile, the uniform elongation evidently reduces, while the fatigue life first sharply increases and then decreases at a stress amplitude of 80 MPa. Such size effects have been discussed based on microstructure characterizations.