Paper number 104
|IN SITU OBSERVATION ON FATIGUE FRACTURE OF MMC|
QUAN Gaofeng*, HE Jiawen*, YANG Shengliang**, YANG Deming** and Lother Wagner***
*State Key Laboratory of Mechanical Behavior of Materials
Xi'an Jiaotong University, Xi'an, 710049, China
**Department of Materials & Applied Chemistry,
National University of Defense Science & Technology, Changsha, 410073, China
***Chair of Materials Technology & Physical Metallurgy, Brandenburg Technical University at Cottbus, Cottbus, 03044, Germany
|Summary|| The fatigue process of SiC fiber reinforced metal matrix composites is observed IN SITU with a scanning electron microscope. It is found that the cracks initiate at the stress-concentrated sites caused by fiber fracturing, which increases as the load cycles increase, then the fibers by the cavity in the matrix fracture shortly. The growths of the cracks are detained by the next fibers. The fracture positions of the neighboring fibers are seldom on the same fractured plane. Almost every fiber fractured more than twice. The main crack of the specimen is evolved in zigzag form by coalescence of the neighboring cracks transversely. The longitudinal propagating of the cracks in the matrix runs close to the fiber-matrix interfaces. The crack initiation cycle number is about 4% of the entire duration. The apparent interfacial bonding strength is evaluated in terms of shear lag model.
||Keywords|| fiber reinforced aluminum matrix composite, IN SITU observation, fatigue crack initiation, crack propagation path, multiple cracking, fatigue life, interfacial bonding strength.
Theme : Metal Matrix Composites ; Microstructure/Properties Relationship
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