Although the theoretical framework supporting the use of non-extensive statistical theory for the study of chemical reaction kinetics and solid-state diffusive reactions is well established, direct evaluation of the parameters involved-such as the case of pair (d, e) appearing in the d-Arrhenius model-in the pertinent experimental data has yet to be generalized. This study proposes the use of ''d-Arrhenius log-log plots'' instead of Arrhenius semilog plots as a tool to determine the kinetic parameters of a reaction and their application to two different solid-state reactions obtained by DSC measurements in an Al-Fe-Si alloy. The paper goes on to show that the data obtained by DSC using the Arrhenius law generate a single k(T), whereas resorting to the Aquilanti-Mundim deformed Arrhenius model generates a set of (d, e) parameter pairs capable of reproducing the experimental data. Different (d, e) pairs generate different k(T) (d = 0, e = Q) corresponding to the Arrhenius pair. The effect of the different (d, e) pairs on the different functions related to the kinetics of the reaction is examined.Graphical Abstract AMDA graph showing linearity for different (d, e) pairs obtained from the precipitation reaction Guinier-Preston zones measured by DSC in an AA8011 commercial alloy (Superior) and Q activation energy for different pairs (bottom). The pair of Arrhenius (0, Q) in both graphs is represented by perpendicular and horizontal lines, respectively.
Aleados de Mg conteniendo 20% y 40% masa de Ti (Mg20Ti) (Mg40Ti), han sido sintetizados por aleación mecánica y caracterizados mediante difracción de rayos-X (DRX) y microscopia electrónica de barrido (MEB con EDS) Los estudios DRX sugieren la incorporación de Ti en la fase Mg, y luego de 40 horas de molienda se aprecia la aparición de dos reflexiones identificadas como óxidos de Mg-Ti. El oxígeno se incorpora al proceso de síntesis debido a las continuas fracturas y soldaduras que ocurren durante la molienda, y hace posible también la formación de una solución sólida de Ti, TiMg. A medida que el tiempo de molienda se incrementa, la talla de cristalitas (D y DS) muestra un decrecimiento hasta valores cercanos a 10 nm, corroborándose este comportamiento mediante microscopía, donde la disminución de talla de partículas alcanza aproximadamente 20 nm. La morfología del aleado va variando, hasta observarse de forma globular o conglomerados de partículas. El análisis EDS confirmó además de Ti y Mg, la presencia de otros elementos.
We have studied the phase transformation kinetics occurring in aluminum alloys containing Mn, Mg, and Mn-Mn-Mg by means of electrical resistivity (rho) and thermoelectric power (deltaS). The alloy samples were annealed isochronally at temperatures ranging from ambient temperature to 615 °C. Both rho and deltaS allowed the separation of several stages of transformation associated to either the precipitation or dissolution of phases that occur during the annealing process. The alloys containing Mn show a strong deltaS growth or a marked r drop between 450 °C and 550 °C, linked to the precipitation of the Mn-rich Al6(Mn,FE) equilibrium phase. While the Mg in aluminum generates a series of maxima and minima of both rho and deltaS associated to the pre-established precipitation sequence: GP Zones ® b' phase ® b phase, a combination of effects ensues in the Mn- and Mg-containing alloys, the Mg effect being enhanced at temperatures below 350 °C and that of the Mn striking the same behavior above such temperature. Our study ascertains that the Mg speeds up the precipitation and lowers the activation energy of the Al6(Mn,Fe) phase, the latter having been evaluated by the multiple temperature method
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