Navegando por Autor "Canté, Manuel Venceslau"
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Artigo Assessing microstructures and mechanical resistances of as-atomized and as-extruded samples of Al-1wt%Fe-1wt%Ni alloy(Elsevier, 2017-01-15) Dessi, João Guilherme; Gomes, Leonardo Fernandes; Peres, Maurício Mirdhaui; Canté, Manuel Venceslau; Spinelli, José Eduardo; Silva, Bismarck LuizCurrent applications of Al–Fe–Ni alloys include Alnico permanent magnets, industrial furnaces, and cladding of nuclear fuel plates. In spite of industrial interest, limited knowledge regarding to inter-relations between microstructure and mechanical resistance can be noted to date. Thus, the aim of the present contribution is, firstly, to analyze the microstructure features of α-Al phase (size and morphology) during atomization of the ternary Al-1wt%Fe-1wt%Ni alloy, including determination of cooling rates and hardness of the obtained powders. Secondly, the nature, size and distribution of intermetallic compounds (IMC), strength and ductility of hot consolidated bulks by extrusion from two different ranges of Al-Fe-Ni powder size (powder size between 75 and 106 μm and powder size up 106 μm and less 180 μm) are examined. The sequence of processes includes nitrogen gas atomization followed by compaction and hot extrusion consolidation at both 350 °C and 400 °C. The procedures to characterize the samples involve X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), Vickers hardness and mechanical tensile tests. Al-rich cells prevailed for either smaller or larger Al-1wt%Fe-1wt%Ni atomized powders with formation of IMCs not only in the cell walls but also precipitated within the α-Al matrix. Strength and ductility of as-extruded samples are found to be consistent with their microstructuresArtigo Solder/substrate interfacial thermal conductance and wetting angles of Bi–Ag solder alloys(Springer, 2015-10-31) Silva, Bismarck Luiz; Bertelli, Felipe; Canté, Manuel Venceslau; Spinelli, José Eduardo; Cheung, Noé; Garcia, AmauriBi–Ag lead-free alloys are considered interesting alternatives to Pb-based traditional solders due to compatible melting point and strength. During soldering, the ability of a liquid alloy to flow or spread over the substrate is crucial for the formation of a metallic bond driven by the physicochemical properties of the liquid solder/solid substrate system. In addition, the wettability is intimately associated with the solder/substrate thermal conductance represented by a heat transfer coefficient, hi. In this work, three Bi–Ag alloys (hypoeutectic—1.5 wt%Ag, eutectic—2.5 wt%Ag and hypereutectic—4.0 wt%Ag) were directionally solidified under upward unsteady state heat flow conditions. Both time-dependent hi profiles and wetting behavior represented by contact angles (θ) were determined for the three alloys examined. The dependence of θ on the alloy Ag content is assessed experimentally. Also, thermal readings collected during directional solidification of the Bi 1.5, 2.5 and 4.0 wt% Ag alloys are used with a view to permitting hi versus time (t) profiles to be computed. It is shown that along a first solidification stage (t < 16 s) the hi values followed the trend experimentally observed by the contact angles for the three alloys examined, while for t > 16 s the volumetric expansion of the Bi-rich phase is shown to have a dominant role inducing a sudden increase in hi. For each alloy a couple of time-dependent hi expressions is needed to represent the entire solidification progress