Effect of a solid solution on the steady-state creep behavior of an aluminum matrix composite
- Defence Metallurgical Research Lab., Hyderabad (India)
- Univ. of California, Davis, CA (United States). Dept. of Chemical Engineering and Materials Science
The effect of an alloying element, 4 wt pct Mg, on the steady-state creep behavior of an Al-10 vol pct SiC{sub p} composite has been studied. The Al-4 wt pct Mg-10 vol pct SiC{sub p} composite has been tested under compression creep in the temperature range 573 to 673 K. The steady-state creep data of the composite show a transition in the creep behavior (regions 1 and 2) depending on the applied stress at 623 and 673 K. The low stress range data (region 1) exhibit a stress exponent of about 7 and an activation energy of 76.5 kJ mol{sup {minus}1}. These values conform to the dislocation-climb-controlled creep model with pipe diffusion as a rate-controlling mechanism. The intermediate stress range data (region 2) exhibit high and variable apparent stress exponents, 18 to 48, and activation energy, 266 kJ mol{sup {minus}1}, at a constant stress, {sigma} = 50 MPa, for creep of this composite. This behavior can be rationalized using a substructure-invariant model with a stress exponent of 8 and an activation energy close to the lattice self-diffusion of aluminum together with a threshold stress. The threshold stress and the creep strength of the Al-Mg-SiC{sub p} composite are compared with those of the Al-Mg-Al{sub 2}O{sub 3f} and 6061 Al-SiC{sub p,w} composites and discussed in terms of the load-transfer mechanism. Magnesium has been found to be very effective in improving the creep resistance of the Al-SiC{sub p} composite.
- OSTI ID:
- 207681
- Journal Information:
- Metallurgical Transactions, A, Journal Name: Metallurgical Transactions, A Journal Issue: 2 Vol. 27; ISSN 0360-2133; ISSN MTTABN
- Country of Publication:
- United States
- Language:
- English
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