| Detailed microscopic examination and metallurgical analysis of dominant microfracture mechanisms of the 2XXX Al-SiC composites under dynamic loading are presented in this study. The materials used here were 2124 Al-7 v/o SiC_p, 2009 Al-15 v/o SiC_w and 2009 Al-15 v/o SiC_P Metallorgraphic investigations of longitudinal sections of most highly deformed areas were made to identify local Void and microcrack formation sites and to observe overall crack propagation paths. Under the quasi-static condition, microvoids initiated predominantly at whisker ends and particle edgs tend to grow along the 45-degree direction to the tensile axis by a localized mode of plastic instability. On the other hand, under dynamic condition, void initiation at whisker(particle) sides and internal whisker(particle) cracking are also observed. The dynamic crack-growth direction of then appears to deviate from the maximum shear -stress direction, so as to interconnect locally developed fracturing events in a rapid manner. |
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