Abstract:Transmission electron microscopy (TEM), X-ray diffraction (XRD), electron backscattered diffraction (EBSD), and tensile tests were used to study the effects of strain rates (0.1, 1 and 9.1 s^-1) on the microstructure and mechanical properties of spray-formed Al-Cu-Mg alloys during large-strain rolling at 420 °C. Results show that during hot rolling, the proportion of high-angle grain boundaries (HAGBs) and the degree of dynamic recrystallization (DRX) initially increase and then decrease, whereas the average grain size and dislocation density show the opposite trend with the increase of the strain rate. In addition, the number of S′ phases in the matrix decreases, and the grain boundary precipitates (GBPs) become coarser and more discontinuous as the strain rate increases. When the strain rate increases from 0.1 to 9.1 s^-1, the tensile strength of the alloy decreases from 492.45 to 427.63 MPa, whereas the elongation initially increases from 12.1% to 21.8% and then decreases to 17.7%.

Key words: spray forming; Al-Cu-Mg alloy; strain rate; microstructure; mechanical properties