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Microstructure Evolution and Mechanical Behavior of Ultrafine Ti-6Al-4V During Low Temperature Superplastic Deformation (Postprint)
AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH WRIGHT-PATTERSON AFB United States
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The influence of microstructure evolution on the low-temperature superplasticity of ultrafine Ti6Al4V was established. For this purpose, the static and dynamic coarsening response and plastic-flow behavior of the alloy with a mean size of sub grains and particles of 0.10.4 m were determined via a series of tension tests at temperatures between 450 and 700 C. Both static and dynamic coarsening exhibited diffusion-controlled r3-vs-time kinetics. However, dynamic coarsening was approximately two orders of magnitude faster than the corresponding static behaviors due to enhanced diffusion through the deformed matrix. A total elongation of 1000 and strain-rate-sensitivity exponent m 0.48 were obtained at 550 C and 2 104 s1. Very limited cavitation was observed in the specimens after superplastic deformation under optimal conditions.
APPROVED FOR PUBLIC RELEASE