High-pressure-torsion-induced segregation, precipitation and grain refinement of Al-(Si, Mg and Cu) binary alloys

• Published in: Journal of materials science & technology Vol. 199; pp. 102 - 113
• Main Authors: Feng, Man, Wu, Qinli, Xue, Jing, Luo, Zhenjiao, Wang, Zhiping, An, Xianghai, Liao, Xiaozhou, Li, Jiehua, Jin, Shenbao, Sha, Gang
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 10.11.2024
• Subjects: Al alloys; Grain refinement; High pressure torsion; Precipitation; Segregation; Precipitation; High pressure torsion; Al alloys; Segregation; Grain refinement
• ISSN: 1005-0302
• DOI: 10.1016/j.jmst.2024.02.046

•Al-1Si, Al-1Mg and Al-1Cu alloys under HPT processing exhibit different grain refinement largely due to their different GB segregation.•HPT-induced decompositions of Al-1Si and Al-1Cu alloys give different precipitation microstructures and grain size evolution.•Unlike Al-1Mg and Al-1Cu alloys, Al-1Si alloy exhibits grain coarsening with increasing HPT revolution above 1.•Segregation and dynamic precipitation have significant effects on ultrafine grain formation. To uncover the effects of segregation and precipitation on grain refinement of metals under severe plastic deformation, high-pressure-torsion (HPT) processing is performed on three binary Al-(Si, Mg, and Cu) alloys with different stability and segregation characteristics. Atom probe tomography analysis reveals that HPT processing induces significant decomposition of Al-1 at% Si and Al-1 at% Cu alloys with coarse Si particles and fine Al2Cu (θ) precipitates formed, but no decomposition of Al-1 at% Mg alloy, with dislocations segregated with Si, Cu, and Mg, and grain boundaries (GBs) only segregated with Cu and Mg. The GB segregation of Cu is stronger than that of Mg and Si, with Cu excess in the range of 1.5–7.0 atoms/nm2, Mg excess in the range of 0–4.0 atoms/nm2, but no Si excess. Interestingly, some GBs without Mg segregation develop a Mg-depletion zone along a single side. All evidences demonstrate that GB segregation and precipitation are responsible for HPT-induced grain refinement of Al-1Mg and Al-1Cu alloys but coarsening of the Al-1Si alloy. Engineering solute distribution is of significance in controlling the ultrafine grain of the Al alloys. [Display omitted]