In-situ TEM study of the microstructure and fracture behavior of SiC{sub w}/2124 Al composites

Conference · Fri Dec 31 04:00:00 EST 1993

OSTI ID:143690

Jung, H C; Yoon, K S; Park, C G ^[1]

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1. Pohang Institute of Science and Technology (Korea, Republic of). Dept. of Materials Science and Engineering

The effect of microstructure on the fracture behavior of 2124 Al composite reinforced with SiC whiskers (SiC{sub w}) has been investigated by using analytical electron microscopy and in-situ TEM deformation technique. The composite was revealed to contain various second-phase particles and crystalline defects, both of which were usually distributed heterogeneously, especially, along the SiC{sub w}/Al interface and the matrix grain boundary. Direct observations of the fracture behavior of SiC{sub w}/2124Al composites have been made during the in-situ tensile straining to fracture in a TEM. Particular attentions were focused on the interaction between a crack and a whisker and the role of SiC{sub w}/Al interface during the initiation and propagation of cracks. Under an applied stress, unusual microcrack formation occurs by the local thinning at SiC{sub w}/Al interfacial region where the whiskers are densely located. In addition, the failure of intermetallic compounds and the SiC whisker itself were also observed. The major crack, then, proceeds by the coalescence of these local microcracks. Various mode of crack propagation were also observed the deflection and bridging of cracks, whisker breakage, and interfacial decohesion. When a crack meets SiC whisker, the propagation is generally delayed by either the deflection of crack path or the bridging of the SiC whisker. However, the breakage of SiC whisker itself or the SiC{sub w}/Al interface followed by a brittle crack propagation was occasionally observed.

• OSTI ID: 143690
• Report Number(s): CONF-930246--; ISBN 0-87339-251-5
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM BASE ALLOYS
COMPOSITE MATERIALS
FRACTURE PROPERTIES
MICROSTRUCTURE
SILICON CARBIDES