STUDY OF PLASTICALLY DEFORMED ICOSAHEDRAL AL-PD-MN SINGLE QUASI-CRYSTALS BY TRANSMISSION ELECTRON-MICROSCOPY

Al-Pd-Mn single-quasicrystals have been plastically deformed at temper atures between 730 and 800 degrees C up to different strain values and analysed in the transmission electron microscope. Dislocations were c reated during deformation. The dislocation density ranged between 1.7 x 10(7) cm(-2) in undeformed samples and 7.8 x 10(8) cm(-2) in materia l deformed at 732 degrees C. Six-dimensional dislocation Burgers vecto rs were determined employing the convergent-beam electron diffraction technique. 87% of these Burgers vectors were oriented parallel to twof old directions in three-dimensional physical space. Their moduli were 0.113, 0.183 and 0.296 nm. The ratio of the phason to the phonon compo nent of the Burgers vectors was found to increase with increasing stra in. A variety of slip systems was observed. In most cases the respecti ve slip plane normals were parallel to fivefold and threefold directio ns.