PLASTIC-DEFORMATION IN ICOSAHEDRAL AL-PD-MN ALLOYS

The deformation characteristics of icosahedral Al70Pd21.5Mn8.5 have been investigated by high temperature creep experiments, and the resultant microstructures have been examined by transmission electron microscopy (TEM). From 730 to 780 degrees C, microstructural analysis revealed that the deformation is controlled by dislocation glide, with an activation energy of 210 +/- 30 kJ/mole and a stress exponent of 1.2 +/- 0.2. From 780 to 810 degrees C, microstructures were characteristic of deformation controlled by dislocation glide and climb. The activation energy and stress exponent were determined to be 1700 +/- 80 kJ/mole and 2.9 +/- 0.3, respectively. Hardness measurements also reflected an increase in dislocation density, as the hardness of the deformed samples was approximately 10% higher than the as-cast sample.