Phase transformations in Al-Ti-Mg powders consolidated by high-pressure torsion: Experiments and first-principles calculations

[摘要] A powder mixture of Al-Ti-Mg with an equal atomic fraction was subjected to severe plastic deformation using high-pressure torsion (HPT) under 6 GPa at room temperature for full consolidation. Microstructural evolution with respect to straining and annealing was examined by X-ray diffraction (XRD) analysis and high-resolution transmission electron microscopy. The XRD analysis revealed that Ti prevails in the consolidated sample and a phase transformation occurs from alpha phase to omega phase during HPT processing while the total fraction of the omega phase increases with straining. Grain refinement to similar to 100 nm was achieved through the HPT processing for 100 revolutions as well as the formation of nanograined intermetallics such as Al3Ti, AlTi3 and TiAl. The hardness gradually increases with straining, and further increases by annealing at 573 K for 1.5 h due to the formation of an Al12Mg17 phase despite the fact that the harder omega phase was reversely-transformed to the softer alpha phase and grains were coarsened to similar to 450 nm. First-principles cal-culations show that Al and Mg elements are dissolved into the omega - Ti during HPT processing. (C) 2021 Elsevier B.V. All rights reserved.

[发布日期] 2021-12-31

[关键词] Severe plastic deformation;High-pressure torsion;Grain refinement;Aluminum-titanium-magnesium (Al-Ti-Mg) alloy;High-resolution transmission electron microscopy (HRTEM)