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

Abstract

To explore the micro-mechanism for the size effect of the mechanical behavior of metallic crystals, the tensile and fatigue behavior of [345] 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 σ YS and a slight decrease in σ UTS take place; meanwhile, the δ evidently reduces, especially as t < 0.6 mm, while the N f 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 [345] Cu single crystal.

New Constitutive Model for the Size Effect on Flow Stress Based on the Energy Conservation Law

“…The orientation and deformation behavior of individual grains is particularly important due to the weak intergranular constraint. The specimen thickness [33] and grain orientation [34] are the key factors affecting the flow stress. In this case, the flow stress of the sheet is more difficult to predict due to the different orientation of individual grains.…”

Thickness-Dependent Tensile Behavior of Cu-Mn Alloys under Different Dislocation Slip Modes

“…Accordingly, the size effect becomes more significant for Cu-Mn alloys. In contrast, the thicker specimen can help decentralize the stress localization due to the improvement of the mobile dislocations [20,21]. It is worth noticing that, compared with wavy-slip dislocation structures, planar slip structures can suppress the annihilation of dislocations and assist the strain-hardening process by reducing the dislocation glide length, leading to the enhancement in plastic defomation capacity [17][18][19].…”