Relationship between Σ3 Boundaries, Dislocation Slip, and Plasticity in Pure Nickel

Abstract

This study investigated the relationship between the Σ3 boundaries, dislocation slip, and plasticity in pure nickel wires after grain boundary (GB) modification. Both quasi in situ tensile tests and simulations were employed. During plastic deformation, twins surrounded by Σ3 boundaries may exhibit a good deformation coordination. With an increase in strain, the slip systems corresponding to the maximum Schmid factor and the actual activated slip systems remain unchanged. Even sub-grains can maintain the dominant slip system of their origin matrix grains. Slip systems with slip planes (111) and (1−1−1) are the most active. Moreover, random boundaries have strong hindering effects on dislocations, and the nearby stress accumulates continuously with an increase in strain. In contrast, Σ3 boundaries demonstrate weak blocking effects and can release the nearby stress due to their unique interfacial structures, which is favorable for improving plasticity. They are more penetrable for dislocations or may react with the piled dislocations. In addition, some Σ3 boundaries can improve their geometrical compatibility factor with an increase in the strain, which enhances the deformation coordination of the grains. The research results provide a better understanding of the plasticizing mechanism for face-centered cubic (fcc) materials after grain boundary modification.

Relationship between the Orientation of the (100) Crystal Plane and Elongation in Ultrathin Electrolytic Copper Foils

“…Dislocations typically move on specific slip planes, which are closely related to slip systems. 32,33 The ease of slip system activation can be analyzed using the Schmid factor (m), where a higher Schmid factor indicates easier slip system activation, better plasticity, and lower yield stress. 34−36 Therefore, EBSD was employed to characterize the Schmid factors of the above ECF samples, as shown in Figure 5.…”

“…Dislocations typically move on specific slip planes, which are closely related to slip systems. , The ease of slip system activation can be analyzed using the Schmid factor ( m ), where a higher Schmid factor indicates easier slip system activation, better plasticity, and lower yield stress. − Therefore, EBSD was employed to characterize the Schmid factors of the above ECF samples, as shown in Figure . From the graphs (a–f), it can be observed that the Schmid factor distribution charts for the six samples are composed of red, orange, and yellow colors, with no appearance of the blue and green colors indicated on the scale.…”