The micromechanisms of fatigue failure of a short alumina-silicate fiber reinforced cast aluminum alloy (A356) are investigated in this study. This composite is a candidate material for automotive applications such as connecting rods, pistons and cylinder liners. In previous studies of the room temperature tensile properties (Canumalla et al., 1995) and the thermal fatigue resistance (Herr et al., 1995), it was found that fibrous inclusions (called shot) in the composite played a significant role in controlling failure. These shot particles, which are caused by improper fiberization during the fiber fabrication process, exist as irregularly shaped globules of alumina-silicate. They can either be hollow or solid, and range in size from 40 to 300 μm in diameter. Although the majority of shot particles are filtered out during the preform fabrication process, the residual shot content can be detrimental to the performance of the composite. The microstructure of the as-cast composite specimens consists of approximately equiaxed dendrites of α-aluminum with the fibers (2 to 6 μm in diameter) distributed primarily in the eutectic between the dendrites (Canumalla et al, 1992). The presence of fibers in the eutectic is believed to be due to the solidification process where the α-aluminum (which solidifies earlier during cooling) nucleated away from the pre-heated fibers.
|Number of pages
|American Society of Mechanical Engineers, Materials Division (Publication) MD
|Published - 1996
All Science Journal Classification (ASJC) codes
- General Engineering