材料期刊网

Complex structures can be regarded as bring derived from a few basic structures via the local twinning at the atomic level. Although quasicrystals and approximants are believed to be the B2 derivatives, the related B2 twinning mode is not known. This paper addresses this problem by analysing the twinning property of Al-Cu approximants in an Al3Cu4 sample. Such an analysis leads to the recognition of the B2 chemical-twinning mode as 180 degrees/[111]B-2, which is responsible for the pentagonal atomic configuration in the Al-Cu approximants as well as for the pseudofivefold B2 twinning observed on quasicrystal surfaces.