Superplasticity and cavitation in Ti-6Al-4V alloy
The superplastic deformation of Ti-6Al-4V at 750/sup 0/-850/sup 0/C and at strain rate 10/sup -4/-10/sup -5/s/sup -1/ has been studied. Continuous and interrupted tensile tests were performed to determine the mechanical behavior of this alloy. The calculated activation energy suggests that the rate controlling mechanism during the deformation was that for lattice diffusion in the ..beta..-phase. The strain rate sensitivity (m approx. = 0.5) remained almost constant, except at strain rate below 2 x 10/sup -5/s/sup -1/. At the low strain rates, a decrease in the strain rate caused an increase in the stress. Only a small number of cavities were found to nucleate in the specimens which were deformed superplastically in continuous tensile tests. However, at high stresses the cavities nucleated at triple grain boundaries of the ..cap alpha..-phase. At intermediate stresses, most of the cavities nucleated at the particle-..cap alpha.. matrix interface. At low stresses, cavities were found to nucleate at triple junction of ..cap alpha.. grains. However, during the grain growth of the ..beta..-phase the cavities were often observed within the ..beta..-phase. The absence of larger number of cavities in Ti-6Al-4V, according to the model is a result of the coating effect of the ..beta..-phase.
- Research Organization:
- California Univ., Davis (USA)
- OSTI ID:
- 6056351
- Country of Publication:
- United States
- Language:
- English
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