Evaluation of the Effects of Stress State and Interfacial Properties on the Behavior of Advanced Metal Matrix Composites.
Abstract
The effects of fiber fraction, fiber orientation and matrix alloy additions on tensile and fatigue behavior were studied in commercially pure magnesium and ZE41A (Mg-4.25Zn-0.5Zr-1.25RE) that were both reinforced with FP alumina fibers. In general, axial properties were not. Off-axis loading resulted in substantial reductions in tensile and fatigue strength in the commercially pure matrix material. Although failure in tensile overload occurred along the weak fiber/matrix interface in off-axis specimens, subcritical fatigue cracks propagated parallel to the fiber direction but through the matrix. The fractographic appearance of these cracks is similar to cyclic cleavage along slip planes. The critical stress intensity for unstable fracture of off-axis material was controlled by a combination of the normal and shear stress components acting on the fiber/matrix interface. The alloying conditions in ZE41A resulted in a slight decrease in axial properties accompanied by a significant improvement in off-axis behavior. These differences were found to be a result of improved matrix and interface strengths and a decrease in fiber strength. The reaction zone product in both materials was determined to be MgO.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1984
- Accession Number
- ADA143911
Entities
People
- G. R. Leverant
- J. E. Hack
- Rachel Page
Organizations
- Southwest Research Institute