The Effect of Additional Severe Plastic Deformation at Elevated Temperatures on the Microstructure and Functional Properties of the Ultrafine-Grained Al–0.4Zr Alloy

Influence of Decreased Temperature of Tensile Testing on the Annealing-Induced Hardening and Deformation-Induced Softening Effects in Ultrafine-Grained Al–0.4Zr Alloy

“…The microstructure of the samples of as-received, HPT and HPT + AN states was studied by electron backscatter diffraction, and transmission electron microscopy in our previous works [ 9 , 14 ], the results of EBSD studies are presented in Table 1 . The initial state of the Al–0.4Zr alloy was characterized by subgrains elongated in the rolling direction with an average length of ~1800 and a width of ~1000 nm (the HAGB fraction was 25%) [ 14 ].…”

“…The formation of nanosized (10–15 nm) Al 3 Zr precipitates on some GBs was observed in in situ annealing experiments in a scanning transmission electron microscope [ 20 ]. As shown earlier, in the Al–0.4Zr alloy in the initial state (before HPT processing), all Zr atoms were dissolved in aluminum matrix [ 4 , 9 , 14 ]. Annealing at 503 K led to the formation of a small amount of nanosized precipitates of the Al 3 Zr phase inside the grains [ 9 , 14 ].…”

“…As shown earlier, in the Al–0.4Zr alloy in the initial state (before HPT processing), all Zr atoms were dissolved in aluminum matrix [ 4 , 9 , 14 ]. Annealing at 503 K led to the formation of a small amount of nanosized precipitates of the Al 3 Zr phase inside the grains [ 9 , 14 ].…”

“…Previously, we studied the influence of high-pressure torsion (HPT) on the microstructure and mechanical properties of the Al–0.4Zr alloy, as well as the heat resistance of the obtained mechanical characteristics of the alloy in the UFG state to short-term annealing (1 h) at temperatures up to 280 °C [ 9 ]. It was shown that the annealing of the UFG Al–0.4Zr alloy for 1 h at temperatures of 230–280 °C results in a unique combination of functional properties—the ultimate tensile strength σ UTS = 200–250 MPa and the electrical conductivity equals 49–50% IACS [ 9 ]—which demonstrates the high potential of such an alloy for use under elevated temperatures, for example, as a wire material for high-voltage power lines. Moreover, the effect of significant additional strengthening after low-temperature annealing of the UFG Al–0.4Zr alloy was revealed [ 9 ].…”

“…It was shown that the annealing of the UFG Al–0.4Zr alloy for 1 h at temperatures of 230–280 °C results in a unique combination of functional properties—the ultimate tensile strength σ UTS = 200–250 MPa and the electrical conductivity equals 49–50% IACS [ 9 ]—which demonstrates the high potential of such an alloy for use under elevated temperatures, for example, as a wire material for high-voltage power lines. Moreover, the effect of significant additional strengthening after low-temperature annealing of the UFG Al–0.4Zr alloy was revealed [ 9 ]. The maximum increases in the yield stress ( σ 0.2 ≈ 65%) and the ultimate tensile strength ( σ UTS ≈ 30%) were reached as a result of annealing at 230 °C for 1 h. At the same time, the plasticity of the UFG alloy remained at a sufficiently high level of ~12%.…”