Abstract
The method of “in-situ tensile testing in SEM” is suitable for investigations of fracture mechanisms because it enables to observe and document deformation processes directly, thank to which the initiation and development of plastic deformation and fracture can be reliably described. With increasing tensile load, local cracks are formed by rupture of large particles and decohesion of smaller particles. Further increase of load leads to the crack growth by coalescence of cavities in the direction from the surface into the specimen centre. Depending on the particle volume fraction, the cracks can be parallel or perpendicular to the load direction. The final rupture takes place in rows of variable density, depending on the volume fractions of carbide (Al₄C₃) and oxide (Al₂O₃) particles.
The aim of the present study is to evaluate the influence of volume fraction of Al₄C₃ particles (8 and 12 vol.%) on the fracture mechanism.

Key words
metal matrix composites, dispersion strengthened Al, “in-situ tensile testing in SEM”, fracture mechanisms

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