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Abstrakt

NiTi alloys are successfully used in engineering and medical applications because of their properties, such as shape memory effect, superelasticity or mechanical strength. A composite with Mg matrix, due to its vibration damping properties, can be characterized by low weight and good vibration damping properties. In this study, a combination of two techniques was used for successful fabrication of Mg composite reinforced by NiTi alloy preform. The porous preforms synthesized by Self-propagating High-temperature Synthesis (SHS) from elemental powders were subsequently infiltrated with Mg by squeeze casting. The effects were examined with scanning electron microscope with EDS detector, X-ray diffraction and microindentation. The inspection has shown well-connected matrix and reinforcement; no reaction at the interface and open porosities fully infiltrated by liquid Mg. Moreover, analysis of samples’ fracture has exhibited that crack propagates inside the Mg matrix and there is no detachment of reinforcement.
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Abstrakt

The preliminary results of the application of open-celled glassy-carbon foam (Cof) in magnesium matrix composites processed by the powder metallurgy method were presented. For the component consolidation, compaction with vertically-torsional vibration and hot-pressing were applied. For the material characterization, the microstructure examination LM and SEM with EDS was employed and also, the porosity and microhardness were measured. An influence of the carbon foam cells’ size on the composite porosity and microhardness was revealed. Additionally, a generation of a few micrometer thin and differently shaped MgO inclusions was observed. Differences in the oxide phase amount, size and shape in the magnesium matrix measured by the quantitative metallography method in the cross-sectioned composite elements were stated. With an increase of the distance from the composite roller top, an increase of the MgO content and microhardness was noticed.
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Abstrakt

The aim of this work is the development of Cu-Al2O3 composites of copper Cu-ETP matrix composite materials reinforced by 20 and 30 vol.% Al2O3 particles and study of some chosen physical properties. Squeeze casting technique of porous compacts with liquid copper was applied at the pressure of 110 MPa. Introduction of alumina particles into copper matrix affected on the significant increase of hardness and in the case of Cu-30 vol. % of alumina particles to 128 HBW. Electrical resistivity was strongly affected by the ceramic alumina particles and addition of 20 vol. % of particles caused diminishing of electrical conductivity to 20 S/m (34.5% IACS). Thermal conductivity tests were performed applying two methods and it was ascertained that this parameter strongly depends on the ceramic particles content, diminishing it to 100 Wm-1K-1 for the composite material containing 30 vol.% of ceramic particles comparing to 400 Wm-1K-1 for the unreinforced copper. Microstructural analysis was carried out using SEM microscopy and indicates that Al2O3 particles are homogeneously distributed in the copper matrix. EDS analysis shows remains of silicon on the surface of ceramic particles after binding agent used during preparation of ceramic preforms.
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Abstrakt

Wear resistance of TiC-cast steel metal matrix composite has been investigated. Composites were obtained with SHSB method known as SHS synthesis during casting. It has been shown the differences in wear between composite and base cast steel. The Miller slurry machine test were used to determine wear loss of the specimens. The slurry was composed of SiC and water. The worn surface of specimens after test, were studied by SEM. Experimental observation has shown that surface of composite zone is not homogenous and consist the matrix lakes. Microscopic observations revealed the long grooves with SiC particles indented in the base alloy area, and spalling pits in the composite area. Due to the presence of TiC carbides on composite layer, specimens with TiC reinforced cast steel exhibited higher abrasion resistance. The wear of TiC reinforced cast steel mechanism was initially by wearing of soft matrix and in second stage by polishing and spalling of TiC. Summary weight loss after 16hr test was 0,14÷0,23 g for composite specimens and 0,90 g for base steel
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