“…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.…”