MICROSTRUCTURE OF Glidcop AL-60

TL;DR

This study provides a detailed microstructural analysis of Glidcop AL-60, revealing nanoparticle types, sizes, and their role in strengthening, which is vital for developing higher field pulsed magnets.

Contribution

It offers a comprehensive TEM and STEM characterization of Glidcop AL-60 microstructure, identifying alumina nanoparticle types, distributions, and their impact on mechanical properties.

Findings

Identified alpha-Al2O3 and eta-Al2O3 nanoparticles in AL-60.

Nanoparticles are 5-30 nm, triangular, with specific crystal orientations.

Dislocations are pinned by alumina particles, indicating Orowan looping as strengthening mechanism.

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 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.