Dynamic recrystallization-dependent high-temperature tensile properties and deformation mechanisms in Al-Mg-Sc-Zr alloys

This research elucidates discontinuous dynamic recrystallization (DDRX)-dependent high-temperature tensile properties and deformation mechanisms in simply extruded Al-7Mg alloys tailored by Sc/Zr ratios. The bimodalgrained Al-7Mg-0.4Sc alloy presents a high elongation to failure of similar to 540% at 400. C and 5 x 10(-4) s(-1). However, such superplastic behavior has not been observed in both coarse-grained Al-7Mg-0.1Sc-0.3Zr and Al-7Mg-0.3Sc0.1Zr alloys. Thermally stable dispersed nano-sized Al-3(Sc,Zr) particles strongly retard DDRX, accompanied by the retention of heterogeneous grain structure in Al-7Mg-0.1Sc-0.3Zr till fracture. The predominance of dislocation slip is proved by analyzing the evolution of texture and dislocations. In contrast, the bimodal grain structure evolves into a homogeneous fine one in Al-7Mg-0.4Sc with tensile deformation proceeding since coarsening Al3Sc precipitates play a weak role in restricting DDRX. The superplasticity in Al-7Mg-0.4Sc is achieved by cooperated mechanisms, i.e., grain boundary sliding (GBS) and dislocation slip as dominant mechanisms, which is accommodated by DDRX in the initial tensile deformation stage, followed by dislocation slip-accommodated GBS in the late stage.

Automated summary

This research reveals the high-temperature tensile properties and deformation mechanisms in simply extruded Al-7Mg alloys tailored by Sc/Zr ratios, specifically focusing on discontinuous dynamic recrystallization (DDRX). The bimodal-grained Al-7Mg-0.4Sc alloy exhibits superplastic behavior with a high elongation to failure of approximately 540% at 400°C and 5 x 10(-4) s(-1). However, this behavior is not observed in the coarse-grained Al-7Mg-0.1Sc-0.3Zr and Al-7Mg-0.3Sc0.1Zr alloys. The superplasticity in Al-7Mg-0.4Sc is achieved through a combination of grain boundary sliding (GBS) and dislocation slip as dominant mechanisms, accompanied by DDRX in the initial tensile deformation stage and dislocation slip-accommodated GBS in the late stage.