Thermal Fatigue Behavior of FP Alumina/Magnesium Composites.
Abstract
The effects of cyclic and isothermal thermal exposure on the axial and transverse tensile strength and axial moduli of 55 volume percent FP-A1-2O3/QH21A Mg composites have been evaluated to understand the cause of thermally induced strength degradation and to help determine the limiting use conditions for these composites. Specific findings are as follows: (1) Thermal cycling of FP-A12O3/QH21A Mg composites to 250 C for 2000 cycles did not cause any appreciable room temperature strength or modulus loss compared with baseline data for untreated composites. In contrast, composites thermally cycled to 350 C showed considerable loss in both axial strength and modulus. No appreciable loss in room temperature transverse tensile strength of composites was measured after thermal cycling. (2) Measurement of the transverse strength and fractographic analysis of thermally cycled composites indicated interface void formation and matrix cracking and fiber debonding as prime contributors to observed strength and modulus losses. These results are consistent with degradation mechanism based on thermal-induced stresses in the matrix. (3) No appreciable loss in the axial dynamic modulus of these composites was observed after isothermal exposure. Small strength losses observed in isothermally heated composites were attributed to matrix softening. (4) The high temperature mechanical properties were not measured for the composites in this study. This would be required to properly design using FP-A12O3/QH21A composites.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 18, 1982
- Accession Number
- ADA117292
Entities
People
- Ramakrishna T. Bhatt