Plasticity of Al-Ni-Co decagonal single quasicrystals

Compression experiments have been performed for Al-Ni-Co decagonal single quasicrystals grown by a floating zone method with different orientations of the compression axes: the tenfold direction (c_∥), a twofold direction perpendicular to it (c_⊥) and a direction inclined from the tenfold direction by about 45° (c_45°). The yield stresses obtained range from 700 to 1050 MPa at 973 K, which are much larger than those previously reported. The anisotropy in the yield stress is less than a factor of two. For the c_45° compressed samples, a slip deformation has been observed on a twofold prismatic slip plane and in the tenfold slip direction. Long straight screw dislocations have been observed by transmission electron microscopy (TEM) in the c_45° compressed samples, indicating the existence of deep Peierls-potential valleys for the dislocation glide. The c_∥ and c_⊥ compressed samples have shown slip deformations along more than two types of pyramidal slip planes.