Generation of extreme grain aspect ratios in severely deformed tantalum at elevated temperatures

Year: 
2017
Month: 
5
Day: 
13
Pages: 
60-63
DOI: 
10.1016/j.scriptamat.2017.04.024
Type: 
Journal Articles
Journal: 
Scripta Materialia
Volume: 
137
Abstract: 

Severe plastic deformation effectively produces nanostructured metals. During deformation these structures undergo repetitive dynamic recovery processes, limiting refinement and aspect ratio. Processing tantalumat elevated temperatures by high pressure torsion allows the synthesis of structures with extreme grain aspect ratios of almost ten. Although the overall restoration processes increase with deformation temperature, reflected in enlarged lamellae thicknesses, they are not effective enough to reduce the lamella length at elevated temperatures. Our results indicate that triple junction motion is impeded below a certain temperature while the efficiency of deformation-induced boundary migration diminishes with temperature, allowing to generate such elongated structures.