Observation and analysis of extended dislocations in an Al–Pd–Mn icosahedral quasicrystal by transmission electron microscopy

Abstract

Extended dislocations including partial dislocations and a stacking fault in Al₇₀Pd₂₀Mn₁₀ icosahedral quasicrystal have been observed and identified for the first time. The diffraction contrast and defocus convergent-beam electron diffraction experiments show that the dissociation of the extended dislocations is of the form 1/2<1 −2 0 0 −2 1> → 1/4<1 −3 1 −1 −1 1>+ 1/4<1 −1 −1 1 −xs3 1> with a stacking fault between these two partial dislocations. For the partial dislocations, the Burgers vector components in physical space b ^¶ _part are along different fivefold axes with a magnitude of 0.17 nm, which is about one seventh of that in complementary space. For the perfect dislocation, the Burgers vector component in physical subspace b ^¶ _perf is along a twofold axis with a magnitude of 0.183 nm, which is about an eleventh of that in complementary space.