An analysis of cavity growth during superplasticity

Miller, David A. and Langdon, Terence G (1979) An analysis of cavity growth during superplasticity. Metallurgical Transactions A, 10, 1869-1874. (doi:10.1007/BF02811731).

Record type: Article

Abstract

Cavity growth at high temperatures may be controlled by vacancy diffusion, giving cavities which are approximately spherical and randomly distributed, or by power-law creep, giving cavities which are elongated and aligned in the direction of the tensile stress. In general, diffusion growth is favored at low total strains, and there is a transition to power-law growth at a critical cavity radius,r c. The value ofr c increases with decreasing strain-rate, so that there is also a transition from predominanly power-law growth at high stress levels to predominantly diffusion growth at low stress levels. Both types of cavities have been observed in superplastic materials, but the diffusion growth rate may be enhanced if the cavity intersects a number of grain boundaries. The analysis is in good agreement with experimental results reported for three diffent superplastic materials.

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