  Glidcop is an oxide-particle-dispersion strengthened copper composite that
has a combination of high mechanical strength and high electrical conductivity.
It has been used as a conductor for 100 T ultrahigh field pulsed magnets by the
National High Magnetic Field Laboratory, USA. In the quest for even higher
field pulsed magnets, material development is crucial. Since the mechanical
properties of a material are often determined by its micro-structure, full
characterization of the microstructure of Glidcop is necessary. In this work,
we studied the microstructure of Glidcop AL-60 using both transmission electron
microscopy (TEM) and scanning transmission electron microscopy (STEM). We
identified both alpha-Al2O3 and cubic eta-Al2O3 nanoparticles in AL-60 and
investigated their size and density distribution. The small alumina particles
eta-Al2O3 nanoparticles with typical size of 5 to 30 nm are of triangular
shape. They have had well defined crystal orientation relation-ship with the Cu
matrix. We observed dislocations pinned by the alumina nanoparticles in
cold-drawn wires. We believed that dislocation bypassing alumina particles via
Orowan looping was the main strengthening mechanism. We observed microcracks
near large particles, demonstrating the detrimental effect of large particles
in AL-60.
