Stress-Induced Grain Growth in an Ultra-Fine Grained Al Alloy

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 45; no. 6; pp. 2673 - 2688
• Main Authors: Lin, Yaojun, Wen, Haiming, Li, Ying, Wen, Bin, Liu, Wei, Lavernia, Enrique J.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.06.2014; Springer; Springer Nature B.V
• Subjects: 2013 Edward DeMille Campbell Memorial Lecture ASM International; Aluminum alloys; Aluminum base alloys; Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Dynamic recrystallization; Exact sciences and technology; Extrusion; Grain boundaries; Grain growth; Materials Science; Mechanical properties; Metallic Materials; Metallurgy; Metals. Metallurgy; Nanotechnology; Physical metallurgy; Powder metallurgy; Stress analysis; Stresses; Structural Materials; Surfaces and Interfaces; Thin Films; Solute Segregation; Fiber Texture Component; Subgrain Size; Subgrain Structure; Grain Boundary; Fine grain structure; Aluminium base alloys; Grain growth; Microstructure
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-014-2258-5

This paper reports on a study of the stress-induced grain growth phenomenon in the presence of second-phase particles and solutes segregated at grain boundaries (GBs) during high-temperature deformation of an ultra-fine grained (UFG) Al alloy synthesized via the consolidation of mechanically milled powders. Our results show that grain growth was essentially inhibited during annealing at 673 K (400 °C) in the absence of an externally applied stress, whereas in contrast, grain growth was enhanced by a factor of approximately 2.7 during extrusion at 673 K (400 °C). These results suggest that significant grain growth during hot extrusion was attributable to the externally applied stresses stemming from the state of stress imposed during extrusion and that the externally applied stresses can overcome the resistance forces generated by second-phase particles and solutes segregated at GBs. The mechanisms underlying stress-induced grain growth were identified as GB migration and grain rotation, which were accompanied by dynamic recovery and possible geometric dynamic recrystallization, while discontinuous dynamic recrystallization did not appear to be operative.