Navegando por Palavras-chave "Metals and alloys"

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    Ag-rich precipitates formation in the Cu-11%Al-10%Mn-3%Ag alloy
    (Elsevier B.V., 2014-12-05) Silva, R. A. G. [UNIFESP]; Paganotti, A. [UNIFESP]; Jabase, L. [UNIFESP]; Adorno, A. T.; Carvalho, T. M.; Santos, C. M. A.; Universidade Federal de São Paulo (UNIFESP); UNESP
    The formation of Ag-rich precipitates in the Cu-11%Al-10%Mn-3%Ag alloy initially quenched from 1123 K was analyzed. the results showed that nanoprecipitates of a Cu-rich phase are produced at about 523 K. in higher temperatures these nanoparticles grow and the relative fraction of Ag dissolved in it is increased, thus forming the Ag-rich phase. (C) 2013 Elsevier B.V. All rights reserved.
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    Bainitic precipitation in the Cu-9 wt.%Al-4 wt.%Mn-5 wt.%Ag alloy
    (Elsevier B.V., 2014-12-05) Adorno, A. T.; Carvalho, T. M.; Magdalena, A. G.; Santos, C. M. A. dos; Silva, R. A. G. [UNIFESP]; UNESP; Universidade Federal de São Paulo (UNIFESP)
    The isothermal kinetics of bainitic precipitation in the Cu-9 wt.%Al-4 wt.%Mn-5 wt.%Ag alloy was studied in the temperature range from 250 to 400 degrees C. the results indicated a diffusion controlled growth process with an activation energy value equal to that for alloys with high degree of order. the presence of Ag seems to enhance the Al diffusion from the matrix to precipitates. (C) 2014 Elsevier B.V. All rights reserved.
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    Effect of Ag addition on phase transitions of the Cu-22.26 at.%Al-9.93 at.%Mn alloy
    (Elsevier B.V., 2013-02-20) Silva, R. A. G. [UNIFESP]; Gama, S. [UNIFESP]; Paganotti, A. [UNIFESP]; Adorno, A. T.; Carvalho, T. M.; Santos, C. M. A.; Universidade Federal de São Paulo (UNIFESP); Univ Estadual Paulista
    The phase transitions that occur in the Cu-22.26 at.%Al-9.93 at.%Mn and Cu-22.49 at.%Al-10.01 at.%Mn-1.53 at.%Ag alloys after slow cooling were studied using differential scanning calorimetry at different heating rates, microhardness changes with temperature, magnetization changes with temperature, scanning electron microscopy and energy dispersion X-ray spectroscopy. the results indicated that the presence of Ag does not modify the transition sequence of Cu-Al-Mn alloy, introduces a new transition due to the (Ag-Cu)-rich precipitates dissolution at about 800K, and changes the mechanism of DO3 phase dissolution. This mechanistic change was analyzed and a sequence of phase transitions was proposed for the reaction. (C) 2013 Elsevier B.V. All rights reserved.
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    Kinetics of bainite precipitation in the Cu69.3Al18.8Mn10.3Ag1.6 alloy
    (Elsevier Science Sa, 2017) Motta, M. B. J. L. [UNIFESP]; Adorno, A. T.; Santos, C. M. A.; Silva, R. A. G. [UNIFESP]
    In this work the kinetics of bainite precipitation in the Cu69.3Al18.8Mn10.3Ag1.6 alloy was studied using measurements of microhardness change with aging time, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analyses, measurements of magnetization change with applied field and high resolution transmission electron microscopy (HRTEM). The results showed that the bainite precipitation is responsible for the hardness increase in the Cu69.3Al18.8Mn10.3Ag1.6 alloy. The activation energy value obtained for the bainite precipitation is lower than that found in the literature. This was attributed to the presence of Ag dissolved in matrix and the occurrence of the Cu3Al(DO3) -> Cu2AlMn(L2(1)) ordering reaction together with the bainite precipitation. (C) 2016 Elsevier B.V. All rights reserved.
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    Martensite decomposition in Cu-Al-Mn-Ag alloys
    (Elsevier B.V., 2014-12-05) Andrade dos Santos, Camila Maria; Adorno, Antonio Tallarico; Galdino da Silva, Ricardo Alexandre [UNIFESP]; Carvalho, Thaisa Mary; UNESP; Universidade Federal de São Paulo (UNIFESP)
    The influence of Mn and Ag additions on the isothermal kinetics of martensite decomposition in the Cu-9wt.%Al alloy was studied using X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXS) and microhardness changes measurements with temperature and time. the results indicated that the reaction is disturbed by the increase of Mn, an effect associated with the increase in the Al-Mn and Cu-Mn atomic pairs, which disturbs Cu diffusion and increases the activation energy for the martensite decomposition reaction. (C) 2013 Elsevier B.V. All rights reserved.
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    Phase transformations and aging of the Cu72.9Al15.0Mn10.5Ag1.6 alloy
    (Elsevier Science Sa, 2016) Santos, Camila Maria Andrade dos; Adorno, Antonio Tallarico; Oda, Natália Yukie [UNIFESP]; Sales, B. O. [UNIFESP]; Silva, L. S. [UNIFESP]; Silva, Ricardo Alexandre Galdino da [UNIFESP]
    The phase transformations and aging of the Cu72.9Al15.0Mn10.5Ag1.6 alloy were studied in the temperature range from 523 to 723 K using measurement of change in microhardness with variation in quenching temperature and aging time, differential scanning calorimetry (DSC), X-ray diffractometry (XRD), magnetization measurements with temperature and applied field, optical microscopy (MO) and high-resolution transmission electron microscopy (HRTEM). The results indicated that the bainitic precipitation is dominant with increase in microhardness and the activation energy value obtained for this process is lower than that reported in the literature due to the occurrence of a diffusion process disturbed by the presence of Ag dissolved in the alloy. (C) 2016 Elsevier B.V. All rights reserved.