Enhanced Densification of Cavitated Dispersion- Strengthened Aluminum by Thermal Cycling
نویسندگان
چکیده
We report experimental data of creep cavity shrinkage for dispersion-strengthened-cast aluminum with about 23 vol pct submicron Al2O3 dispersoids, annealed isothermally or subjected to thermal cycling without applied stress. Thermal cycling is found to increase the rate of densification by a factor of 3 to 5.5 relative to isothermal annealing at the upper cycling temperature, allowing for recovery of full theoretical density in a shorter time. Isothermal densification is discussed in light of a diffusive cavity shrinkage mechanism, and a model considering thermal mismatch stresses is employed to rationalizethe enhanced rate of densificationobserved during thermal cycling. Intermittent thermal-cycling densification is shown to improve creep life of dispersion-strengthened aluminum through the suppression of tertiary damage accumulation processes.
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