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  • Studies of M▫$g_2$▫Sn-based composites
    Kevorkijan, Varužan ; Škapin, Srečo D.
    Single phase Mg2Sn powders were successfully reaction-synthesized from the elements and applied for the preparation of Mg2Sn-based composites of different nature, microstructure and combination of ... properties. These were fully dense (95 % T.D.) Mg- and Al-metal matrix composites (MMCs) reinforced with either Mg2Sn particles or mixtures of Mg2Sn with TiC or TiB2 particulates by infiltration of porous Mg2Sn preforms with molten magnesium or aluminium; and (ii) Mg2Sn intermetallic matrix composites (IMCs) discontinuously reinforced with TiC and TiB2 particles by pressureless sintering. The microstructures of the composite samples were examined using scanning electron microscopy (SEM-EDS) and X-ray powder diffraction (XRD). The mechanical properties were evaluated by Vickers hardness measurements performed at room temperature, while the fracture toughness of the specimens was determined by applying the indentation method. Based on the data accumulated, an evaluation of the mechanical properties of these composites on the basis of the volume content of different constituents was performed. Moreover, the ability of various microstructures obtained by pressureless infiltration and sintering for tailoring the desired combination of mechanical properties. (e.g. toughening in combination with hardness) was also investigated and reported. Thus, the infiltration led to MMCs with different microstructures and mechanical properties, depending on the infiltrant applied. The samples infiltrated with molten magnesium possessed characteristic lamellar ( gChinese script h) eutectic microstructure and thereby an enhanced fracture toughness (up to 7.7 MPa Em1/2 in non-reinforced and 5.8 MPa Em1/2 in reinforced counterparts), and in combination with Vickers hardness were superior to those of conventional Mg-Sn alloys. On the other hand, although the mechanical response (Vickers hardness) of samples infiltrated with aluminium was even better than in counterparts infiltrated with magnesium, the absence of the gChinese script h microstructure was observed to have a detrimental influence on fracture toughness, which was significantly lower in these samples. The densification of Mg2Sn matrix discontinuously reinforced with TiC or TiB2 ceramic reinforcement performed bya non-reactive, solid-state sintering, resulted in samples with high density (95% T.D.) and different combinations of mechanical properties compared to MMCs obtained by infiltration. The Vickers hardness of sintered IMCs were much higher than in MMCs obtained by infiltration, with the exception of the fracture toughness which was reduced below 1.8 MPa Em1/2.
    Source: Metalurgija = Journal of metallurgy. - ISSN 0354-6306 (Vol. 16, no. 1, 2010, str. 47-61)
    Type of material - article, component part
    Publish date - 2010
    Language - english
    COBISS.SI-ID - 14406422

    Link(s):

    http://www.metalurgija.org.rs/mjom/Vol16/No1/5_Kevorkijan_MJoM_1601.pdf

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