Deformation behaviors of Cu bicrystals with an inclined twin boundary at multiple scales

doi:10.1016/j.jmst.2016.11.030

Abstract

Abstract:

Cu bicrystals of different sizes with a sole twin boundary (TB) inclined at 45° with respect to the loading direction were deformed under unidirectional and cyclic loading, respectively. It is found that the slip bands (SBs) parallel to the TB can be activated near the TB at all scales without obeying the Schmid’s law. It is concerned with the local stress enhancement in the macroscale while it is more closely related to the scarce dislocation sources in the microscale. Moreover, a wedge-shaped zone formed near the TB in the microscale ascribed to the limited specimen size.

Key words: Bicrystal, Micropillar, Twin boundary, Schmid factors, Size effect

Li L.L., Zhang Z.J., Zhang P., Tan J., Yang J.B., Zhang Z.F.. Deformation behaviors of Cu bicrystals with an inclined twin boundary at multiple scales[J]. J. Mater. Sci. Technol., 2017, 33(7): 698-702.

Figures/Tables 4

Fig. 1. (a) Compression stress-strain curves of the bicrystal micropillars and the tension and compression stress-strain curves of the bulk bicrystals. (b) Compression stress-strain curves of the two component single crystal micropillars. M: (<1 4 5>) and T: (<1 6 24>).

Fig. 2. Surface morphologies of the single crystal micropillars. (a) M-3, (b) M-2, (c) T-1, (d) T-3.

Fig. 3. Surface morphologies of the bicrystal micropillars. (a) B-4 before compression; (b) B-2 after compression; (c) B-4 after compression; (d) local enlarged image of B-4 after compression. The upper grain is the M grain while the lower one is the T grain.

Fig. 4. (a) Slip morphologies of the bulk bicrystal with a tensile strain of ～2%; (b) slip morphology of the bulk bicrystal with a compressive strain of ～2%; (c) slip morphology and (D) TB fatigue cracking behavior of bulk bicrystal. The right grain is M grain while the left one is the T grain.

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