Microstructure of Glidcop AL-60

Abstract

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 microstructure, 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 α-Al2O3 and cubic η-Al2O3 nanoparticles in AL-60 and investigated their size and density distribution. The small alumina particles η-Al2O3 nanoparticles with typical size of 5 to 30 nm are of triangular shape. They have had well defined crystal orientation relationship 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.