Characterization of Cu Distribution in an Al-0.3%Cu Alloy Cold Rolled to 98%

Abstract

Abstract. In this study, the distribution of Cu element in a Al (99.9996% purity)-0.3%Cu alloy cold rolled to 98% has been characterized in detail by using three-dimensional atom probe (3DAP) and ChemiSTEM techniques. The cold rolled structure is a typical high strain lamellar structure with an average boundary spacing of 200 nm, indicating a strong role of the small amount of Cu element in stabilizing the microstructure to form the fine scale structure. A heavy segregation of Cu element in the lamellar boundaries of high angles has been observed and the Cu concentration in the boundaries can be as high as 20 times of the nominal concentration of the alloy, which is considered as the main reason for a formation of a stable nanoscale lamellar structure.

Strengthening mechanisms and Hall-Petch stress of ultrafine grained Al-0.3%Cu

“…Nevertheless, after annealing at temperatures higher than 200 ºC, a large number of particles have precipitated in the matrix and at the grain boundaries [28]. The particle density of the 250 ºC annealed sample was measured from SEM electron channeling contrast (ECC) images and the average spacing between the particles was determined to be ~ 1.9 µm.…”

Segregation and precipitation stabilizing an ultrafine lamellar-structured Al-0.3%Cu alloy

“…Distribution of Cu atoms at boundaries in the deformed structure has been investigated by using ChemiSTEM-EDS and APT. According to our previous work [22] , the vast majority of the lamellar structure is free of particles, although a few small particles can be observed lying at the lamellar boundaries. Here, a new example of Cu distribution in the deformed sample combining EDS mapping and TEM characterization is presented in Fig.…”

“…Recently, we fabricated an ultrafine lamellar-structured Al-0.3%Cu alloy [21][22][23] by adding 0.3%wt oxygen-free high conductivity copper into a high purity (99.9996%) Al matrix and cold rolling to a thickness reduction of 98%. Our previous post mortem studies have shown that continuous coarsening of the deformed lamellar structure takes place during recovery annealing [21] and that the segregation of Cu solutes and subsequent precipitation of Al 2 Cu particles preferentially occur at the lamellar boundaries [ 21 , 22 ].…”