Orientation dependence of mechanically induced grain boundary migration in nano-grained copper

Formation of Nanolaminated Structure with Enhanced Thermal Stability in Copper

“…Corresponding to the microstructural gradients, a gradient distribution of microhardness can be detected in the deformed layer, as plotted in Figure 1c. The NL layer exhibits a high hardness of 2.1 GPa, 17% higher than that of NG sample with similar grain size [25]. [25].…”

“…The NL layer exhibits a high hardness of 2.1 GPa, 17% higher than that of NG sample with similar grain size [25]. [25].…”

“…The rods were machined to a diameter of ~10 mm and then subjected to SMGT (BYJC-OKUMA, Beijing, China) for 7 passes. The principle and setup of the SMGT were introduced by previous works [ 5 , 21 , 22 , 25 ]. During SMGT processing, the rod sample rotated at a velocity of 100 r/min while a polished hemispherical WC/Co tip (Φ = 6 mm) penetrated the sample surface by 40 μm deep and slid along the sample at a velocity of 2.5 mm/min.…”

“…The roughly equiaxed NG sample in Ref. [ 25 ] processed by SMGT at liquid nitrogen temperature (LNT) is also included for comparison.…”

“…In addition to grain size, deformation conditions, such as temperature and strain rate, et al, also affect deformation mechanism significantly [ 23 ], which provides a possible way to generate NL structure in Cu with boundary spacing smaller than 200 nm. In our recent study about tension induced GBM in nanograined (NG) Cu [ 25 ], it has been found that full dislocation motion plays a key role in mechanically induced GBM and results in an increasing fraction of low angle GBs. In other word, although the deformation in Cu with grain size range from ~200 nm to 70 nm can be dominated by mechanically induced GBM, low angle GBs are still generating through full dislocation motions in this process.…”