An Investigation of Cavity Growth Rate in Superplastic Al and Mg Alloys

Fine-grained 5083 Al alloy and AZ91 Mg alloy showed superplastic behavior. The plasticitycontrolled growth rates of cavities during superplastic deformation for the Al alloy and Mg alloy were investigated. The cavity volume fraction for the Mg alloy was larger than that for the Al alloy. However, the cavity growth rate for the Mg alloy was lower than that for the Al alloy.

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Cavity growth rate in superplastic 5083 Al and AZ31 Mg alloys

Journal of Materials Research ◽

10.1557/jmr.2004.0431 ◽

2004 ◽

Vol 19 (11) ◽

pp. 3382-3388 ◽

Cited By ~ 13

Author(s):

Yasumasa Chino ◽

Hajime Iwasaki ◽

Mamoru Mabuchi

Keyword(s):

Growth Rate ◽

Grain Boundary ◽

Cavity Growth ◽

Grain Boundary Sliding ◽

Mg Alloy ◽

Al Alloy ◽

Az31 Mg Alloy ◽

Boundary Sliding ◽

Cavity Growth Rate ◽

5083 Al Alloy

The plasticity-controlled growth rate of cavities during superplastic deformationwas statistically investigated for 5083 Al alloy and AZ31 Mg alloy. When the cavity growth rate was evaluated on the basis of macroscopic strain calculated using the displacement of the specimen, the growth rate for the Al alloy was larger than thatfor the Mg alloy. However, the growth rate of the Al alloy was in agreement withthat of the Mg alloy when the cavity growth rate was evaluated on the basis of the microscopic strain due to grain boundary sliding. The results obtained lead to two conclusions: (i) the rate of cavity growth is not affected by the kind of materials,that is, the nature of the grain boundary, and (ii) the microscopic strain due to grain boundary sliding should be used to evaluate exactly the rate of cavity growth for superplastic deformation.

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Numerical Analysis of the Effect of Diffusion and Creep Flow on Cavity Growth

Volume 9: Eighth International Conference on Creep and Fatigue at Elevated Temperatures ◽

10.1115/creep2007-26631 ◽

2007 ◽

Author(s):

Frederick W. Brust ◽

Joonyoung Oh

Keyword(s):

Growth Rate ◽

Numerical Method ◽

Cavity Growth ◽

Volume Growth ◽

Numerical Results ◽

Shape Evolution ◽

Cavity Volume ◽

Cavity Shape ◽

Cavity Growth Rate ◽

Fully Coupled

In this paper, intergranular cavity growth in regimes, where both surface diffusion and deformation enhanced grain boundary diffusion are important, is studied. In order to continuously simulate the cavity shape evolution and cavity growth rate, a fully-coupled numerical method is proposed. Based on the fully-coupled numerical method, a gradual cavity shape change is predicted and this leads to an adverse effect on the cavity growth rates. As the portion of the cavity volume growth due to jacking and viscoplastic deformation in the total cavity volume growth increases, the initially spherical cavity evolves to V-shaped cavity. The numerical results are physically more realistic compared to results in the previous studies. The present numerical results suggest that the cavity shape evolution and cavity growth rate based on an assumed cavity shape, whether spherical or crack-like, cannot be used in this regime due to transitional coupled growth mechanisms.

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Cavitation in a Uniaxially deformed Superplastic Al-Mg Alloy

MRS Proceedings ◽

10.1557/proc-601-61 ◽

1999 ◽

Vol 601 ◽

Cited By ~ 1

Author(s):

D. H. Bae ◽

A. K. Ghosh

Keyword(s):

Strain Rate ◽

Volume Fraction ◽

Cavity Growth ◽

Tensile Tests ◽

Strain Rate Range ◽

Cavity Volume ◽

Fine Grained ◽

Cu Alloy ◽

Deformable Particles ◽

The Matrix

AbstractCavitation caused by superplastic straining of a fine-grained Al-Mg-Mn-Cu alloy under uniaxial tension has been systematically evaluated. Tensile tests were conducted in the strain-rate range of 10−4s−1 to 10−2s−1 and in the temperature range of 450°C to 550°C. Measurements of the number and size of cavities were made by image analysis through optical microscopy on tested specimens. With increasing imposed strain, the cavity population density increases. Cavity growth has been found to be primarily due to the plastic deformation of the matrix. These results are characterized by the total volume fraction of cavities which is found to increase exponentially with strain. However, the dependencies of cavity volume fraction on strain-rate and temperature are not straightforward and the notion of just a few large cavities controlling the total cavity volume is not always true. Attempts to explain these complex dependencies have been carried out based on the concepts of debonding between the matrix and non-deformable particles, the continuous nucleation of new cavities, and plasticity-based cavity growth for large cavities.

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