Papers by Author: M.V. Markushev

Abstract: The effects of severe plastic deformation (SPD) by isothermal rolling at the temperature of liquid nitrogen combined with prior- and post-SPD heat treatment, on microstructure and hardness of Al-4.4%Cu-1.4%Mg-0.7%Mn (D16) alloy were investigated. It was found no nanostructuring even after straining to 75%. Сryodeformation leads to microshear banding and processing the high-density dislocation substructures with a cell size of ~ 100-200 nm. Such a structure remains almost stable under 1 hr annealing up to 200oC and with further temperature increase initially transforms to bimodal with a small fraction of nanograins and then to uniform coarse grained one. It is found the change in the alloy post–SPD aging response leading to more active decomposition of the preliminary supersaturated aluminum solid solution, and to the alloy extra hardening under aging with shorter times and at lower temperatures compared to T6 temper.

Abstract: The effects of equal channel angular pressing (ECAP), further heat treatment and rolling on the structure and room temperature mechanical properties of the commercial aluminum alloys 6061 (Al-0.9Mg-0.7Si) and 1560 (Al-6.5Mg-0.6Mn) were investigated. It has been shown that the strength of the alloys after ECAP is higher than that achieved after conventional processing. Prior ECAP solution treatment and post-ECAP ageing can additionally increase the strength of the 6061 alloy. Under optimal ageing conditions a yield strength (YS) of 434 MPa and am ultimate tensile strength (UTS) of 470 MPa were obtained for the alloy. Additional cold rolling leads to a YS and UTS of 475 and 500 MPa with 8% elongation. It was found that the post-ECAP isothermal rolling of the 1560 alloy resulted in the formation of a nano-fibred structure and a tensile strength (YS = 540 MPa and UTS = 635 MPa) that has never previously been observed in commercial non-heat treatable alloys.