Article ID Journal Published Year Pages File Type
7972089 Materials Science and Engineering: A 2018 22 Pages PDF
Abstract
An ultrafine microstructure consisting of α grains (~ 0.51 µm) and a small amount of β phase was successfully achieved in a friction stir-processed (FSPed) Ti-6Al-4V alloy. The fraction of high angle grain boundaries (HAGBs) with random crystallographic orientations reached 89.3% revealed that dynamic recrystallization was responsible for the ultra-grain refinement mechanism during friction stir processing (FSP). Low-temperature superplasticity (LTSP) of such an ultrafine microstructure was demonstrated in the temperature range of 550-650 °C and strain rates of 1 × 10−4-3 × 10−3 s−1. Specifically, an extremely superior LTSP of 1130% was achieved at 600 °C and 3 × 10−4 s−1, which was explained by means of the ultrafine equiaxed grains, a large proportion of HAGBs with random orientations as well as the presence of β phase. The predominant superplastic deformation mechanism was considered as grain boundary sliding associated with grain boundary diffusion.
Related Topics
Physical Sciences and Engineering Materials Science Materials Science (General)
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