Effects of thickness and precracking on the fracture toughness of particle-reinforced Al-alloy composites
- Systran Corp., Dayton, OH (United States)
- UES, Inc., Dayton, OH (United States)
- Air Force Research Lab., Wright-Patterson, AFB, OH (United States). Materials and Manufacturing Directorate
The effect of specimen thickness on the fracture toughness of a powder metallurgically processed 7093 Al/SiC/15p composite was evaluated in different microstructural conditions. The fracture toughness in the underaged condition increased significantly with a decrease in specimen thickness, even at thicknesses well below the value specified by ASTM-E 813 for a valid J{sub Ic} test. The influence of thickness was considerably lower in the peak-aged (PA) condition. This relative insensitivity is believed to be due to the low strain to failure associated with severe flow localization in the PA condition. The effect of precracking on the fracture toughness of discontinuously reinforced aluminum (DRA) was also evaluated. The dependence of fracture toughness on specimen thickness and precracking is explained in terms of the hydrostatic stress, which has a strong influence on the plastic straining capability of the DRA material. The fracture toughness was modeled using a critical strain formulation, with the void growth strain dependent on hydrostatic stress through the Rice and Tracey model. The predicted toughnesses for the thick and thin specimens were in good agreement with the experimental data.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 616499
- Journal Information:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Vol. 29, Issue 4; Other Information: PBD: Apr 1998
- Country of Publication:
- United States
- Language:
- English
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