Abstract
The stress partitioning between phases, phase stress relaxation as well as origins of Al/SiCp composite strengthening are studied in the present work. In this aim, the measurements of lattice strains by neutron diffraction were performed in situ during tensile test up to sample fracture. The experimental results were compared with results of elastic–plastic self-consistent model. It was found that thermal origin phase stresses relax at the beginning of plastic deformation of Al/SiCp composite. The evolution of lattice strains in both phases can be correctly simulated by the elastic–plastic self-consistent model only if the relaxation of initial stresses is taken into account. A major role in the strengthening of the studied composite plays a transfer of stresses to the SiCp reinforcement, however the hardness of Al metal matrix is also important.
Highlights
Metal Matrix Composites (MMC) are an interesting alternative to classical alloys
Strength and hardness of aluminium can be improved through alloying and heat treatment leading to precipitation or age hardening by the phases precipitated in a solid state reaction, as is in the case of the classical Al-Cu-Mg alloys, or through the strengthening by particles insoluble during the powder compaction technology, as in the case of the composites reinforced by silicon carbide particles
The reason for interphase stresses in the initial samples is a difference in coefficient of thermal expansion (CTE) values for the composite components (Table 2)
Summary
Metal Matrix Composites (MMC) are an interesting alternative to classical alloys Their superior mechanical properties—in comparison to classical alloys—are their unique stiffness, high specific strength and/or ductility, as well as improved wear resistance. The advantage of diffraction methods is that the mechanical behaviour of different phases of polycrystalline material can be independently studied during sample loading [cf 4–10]. This method enables measuring of the lattice strains/stresses selectively for Al-matrix and S iCp—reinforcement constituents, only for the crystallites contributing to the recorded diffraction peaks [cf 11–14].
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