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(parallel to)) a twofold direction perpendicular to it (c(perpendicular to)) and a direction inclined from the tenfold direction by about 45 degrees (c(45 degrees)). 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 degrees) 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 degrees) compressed samples, indicating the existence of deep Peierls-potential valleys for the dislocation glide. The c(parallel to) and c(perpendicular to) compressed samples have shown slip deformations along more than two types of pyramidal slip planes. (C) 2000 Elsevier Science B.V. All rights reserved.