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Papers by Amauri Garcia

Research paper thumbnail of Corrosion Performance Based on the Microstructural Array of Al-Based Monotectic Alloys in a NaCl Solution

Journal of Materials Engineering and Performance, 2014

Research paper thumbnail of Microstructure–wear behavior correlation on a directionally solidified Al–In monotectic alloy

Tribology International, 2013

ABSTRACT Al–In monotectic alloys are potential alternatives for application in the manufacture of... more ABSTRACT Al–In monotectic alloys are potential alternatives for application in the manufacture of wear-resistant automotive components, such as cylinder liners and journal bearings. The comprehension regarding the development of distinct microstructures of monotectic alloys and their interrelation with wear behavior are challenges of prime importance. The present study aims to contribute to a better understanding of the relationship between the scale of the minority phase of the monotectic microstructure and the corresponding wear behavior. Transient directional solidification experiments were carried out with an Al–5.5 wt% In alloy with a view to provide samples with significant differences in the microstructural scale along the casting length. The results of wear tests permitted an experimental quantitative expression correlating the wear volume (V) with both the interphase spacing between indium droplets (λ) and time of wear tests (t) to be proposed. The increase in λ is shown to improve the wear resistance. The effect of λ on V becomes more significant as the sliding distance (or time) is increased.

Research paper thumbnail of EIS parameters and cell spacings of an Al–Bi alloy in NaCl solution

Electrochimica Acta, 2013

ABSTRACT This present study is focused on the evaluation of the effect of the cell spacing of as-... more ABSTRACT This present study is focused on the evaluation of the effect of the cell spacing of as-cast Al-2 wt.% Bi alloy formed by droplet-like bismuth particles distributed in the Al matrix, on the corrosion response. EIS parameters and polarization curves obtained in a 0.5 M NaCl solution at room temperature are discussed. It was found that with the decrease in the cell spacing, the corrosion current density and polarization resistance increases and decreases, respectively. This corrosion behavior was attributed to strains that are generated at the borders between the Al-matrix and droplet-like Bi particles.

Research paper thumbnail of Electrochemical behavior of an Al-Fe-Ni alloy affected by nano-sized intermetallic particles

Research paper thumbnail of Inter-relation of Microstructural Features and Dry Sliding Wear Behavior of Monotectic Al–Bi and Al–Pb Alloys

Tribology Letters, 2014

ABSTRACT Immiscible Al-based alloys of monotectic composition have a particular feature of minori... more ABSTRACT Immiscible Al-based alloys of monotectic composition have a particular feature of minority phases embedded into the Al-rich matrix. The disseminated particles may act as in situ self-lubricating agents due to their lower hardnesses compared with that of the Al-rich matrix, favoring good tribological behavior. There is a lack of systematic fundamental studies on the microstructural evolution of monotectic alloys connected to application properties. In the present investigation, the monotectic Al-1.2wt%Pb and Al-3.2wt%Bi alloys have been chosen to permit the effect of microstructural parameters on the wear behavior to be analyzed. Directional solidification experiments were carried out under transient heat flow conditions allowing a large range of cooling rates to be experienced, permitting a representative variation on the scale of the microstructure to be examined. Samples of the monotectic alloys having different interphase spacing, λ, have been subjected to microadhesive wear tests, and experimental laws correlating the wear volume with the microstructural interphase spacing and test time are proposed. It was found that microstructural features such as the interphase spacing and the morphology of the minority phase play a significant role on the wear process and that for the alloys examined λ exhibits opposite effects on the corresponding wear volume.

Research paper thumbnail of Growth of tertiary dendritic arms during the transient directional solidification of hypoeutectic Pb–Sb alloys

Philosophical Magazine, 2011

Despite the importance of a complete characterization of dendritic patterns in castings, the avai... more Despite the importance of a complete characterization of dendritic patterns in castings, the availability of studies on the development of tertiary dendrite arms is scarce in the literature. In the present study, the tip cooling rate, local solidification time, primary and tertiary dendrite arm spacings have been determined in Pb–Sb alloys castings directionally solidified under unsteady-state heat flow conditions. The alloys compositions experimentally examined are widely used in the as-cast condition for the manufacture of positive and negative grids of lead-acid batteries. The initial growth of tertiary dendritic arms from the secondary branches was found to occur only for a Pb–3.5 wt% Sb alloy at cooling rates in the range 0.4–0.2 K/s, with no evidence of this spacing pattern for Pb–Sb alloys having lower solute content. Tertiary dendritic branches have been observed along the entire casting lengths for alloys of the Pb–Sb hypoeutectic range having compositions higher than 4.0 wt% Sb. It is shown that a power function experimental law with a characteristic −0.55 exponent is able to characterize the tertiary spacing evolution with the solidification cooling rate for alloys compositions ≥4.0 wt% Sb. The only exception was the Pb–3.5 wt% Sb alloy for which λ3 exhibited significant lower values when compared with the experimental values obtained for the other Pb–Sb alloys for a same solidification cooling rate.

Research paper thumbnail of EIS and potentiodynamic polarization studies on immiscible monotectic Al–In alloys

Electrochimica Acta, 2013

Research paper thumbnail of The effect of melt temperature profile on the transient metal/mold heat transfer coefficient during solidification

Materials Science and Engineering: A, 2005

Research paper thumbnail of Investigation of intermetallics in hypoeutectic Al–Fe alloys by dissolution of the Al matrix

Intermetallics, 2009

During the non-equilibrium solidification typical of DC (direct chill) castings a range of coolin... more During the non-equilibrium solidification typical of DC (direct chill) castings a range of cooling rates occur from the surface to the casting center, and can cause the formation of metastable intermetallic phases (AlmFe, Al6Fe, etc.) in addition to the stable Al3Fe phase. The extensive presence of the plate-like Al3Fe phase in the as-cast structure adversely influences the mechanical properties of

Research paper thumbnail of Optimization of the zone melting of materials

Research paper thumbnail of Purification of iron and its magnetic properties characterization

Research paper thumbnail of Method of characterization of magnetic parameters in pure iron-carbon alloys

Research paper thumbnail of THE APPLICATION OF A NEW HEAT-FLOW MODEL TO PLANAR FREEZING IN STATIC AND CONTINUOUS-CASTING OF STEELS

Research paper thumbnail of Mathematical model for the unidirectional solidification of metals: II. Massive molds

Metallurgical Transactions B, 1979

Research paper thumbnail of Analytical technique for the determination of solidification rates during the inward freezing of cylinders

Journal of Materials Science, 1983

Research paper thumbnail of The application of a new solidification heat flow model to splat cooling

Journal of Materials Science, 1981

Research paper thumbnail of Control of the Directional Solidification of Aluminum-Copper Ingots

Research paper thumbnail of Heat Transfer Conditions of the Metal/Mold System Affecting the Refinement of the Silumin(Al-12 per cent Si) Solidification Structure

Research paper thumbnail of Calculation of the Time and Temperature Distribution in the Solidification of Nonferrous Metals. I.--Case of Water Cooled Molds

Research paper thumbnail of Heat Transfer in the Metal/Mold System in Refining the As-Cast Structures of Silumin(Al-12 per cent Si)

Research paper thumbnail of Corrosion Performance Based on the Microstructural Array of Al-Based Monotectic Alloys in a NaCl Solution

Journal of Materials Engineering and Performance, 2014

Research paper thumbnail of Microstructure–wear behavior correlation on a directionally solidified Al–In monotectic alloy

Tribology International, 2013

ABSTRACT Al–In monotectic alloys are potential alternatives for application in the manufacture of... more ABSTRACT Al–In monotectic alloys are potential alternatives for application in the manufacture of wear-resistant automotive components, such as cylinder liners and journal bearings. The comprehension regarding the development of distinct microstructures of monotectic alloys and their interrelation with wear behavior are challenges of prime importance. The present study aims to contribute to a better understanding of the relationship between the scale of the minority phase of the monotectic microstructure and the corresponding wear behavior. Transient directional solidification experiments were carried out with an Al–5.5 wt% In alloy with a view to provide samples with significant differences in the microstructural scale along the casting length. The results of wear tests permitted an experimental quantitative expression correlating the wear volume (V) with both the interphase spacing between indium droplets (λ) and time of wear tests (t) to be proposed. The increase in λ is shown to improve the wear resistance. The effect of λ on V becomes more significant as the sliding distance (or time) is increased.

Research paper thumbnail of EIS parameters and cell spacings of an Al–Bi alloy in NaCl solution

Electrochimica Acta, 2013

ABSTRACT This present study is focused on the evaluation of the effect of the cell spacing of as-... more ABSTRACT This present study is focused on the evaluation of the effect of the cell spacing of as-cast Al-2 wt.% Bi alloy formed by droplet-like bismuth particles distributed in the Al matrix, on the corrosion response. EIS parameters and polarization curves obtained in a 0.5 M NaCl solution at room temperature are discussed. It was found that with the decrease in the cell spacing, the corrosion current density and polarization resistance increases and decreases, respectively. This corrosion behavior was attributed to strains that are generated at the borders between the Al-matrix and droplet-like Bi particles.

Research paper thumbnail of Electrochemical behavior of an Al-Fe-Ni alloy affected by nano-sized intermetallic particles

Research paper thumbnail of Inter-relation of Microstructural Features and Dry Sliding Wear Behavior of Monotectic Al–Bi and Al–Pb Alloys

Tribology Letters, 2014

ABSTRACT Immiscible Al-based alloys of monotectic composition have a particular feature of minori... more ABSTRACT Immiscible Al-based alloys of monotectic composition have a particular feature of minority phases embedded into the Al-rich matrix. The disseminated particles may act as in situ self-lubricating agents due to their lower hardnesses compared with that of the Al-rich matrix, favoring good tribological behavior. There is a lack of systematic fundamental studies on the microstructural evolution of monotectic alloys connected to application properties. In the present investigation, the monotectic Al-1.2wt%Pb and Al-3.2wt%Bi alloys have been chosen to permit the effect of microstructural parameters on the wear behavior to be analyzed. Directional solidification experiments were carried out under transient heat flow conditions allowing a large range of cooling rates to be experienced, permitting a representative variation on the scale of the microstructure to be examined. Samples of the monotectic alloys having different interphase spacing, λ, have been subjected to microadhesive wear tests, and experimental laws correlating the wear volume with the microstructural interphase spacing and test time are proposed. It was found that microstructural features such as the interphase spacing and the morphology of the minority phase play a significant role on the wear process and that for the alloys examined λ exhibits opposite effects on the corresponding wear volume.

Research paper thumbnail of Growth of tertiary dendritic arms during the transient directional solidification of hypoeutectic Pb–Sb alloys

Philosophical Magazine, 2011

Despite the importance of a complete characterization of dendritic patterns in castings, the avai... more Despite the importance of a complete characterization of dendritic patterns in castings, the availability of studies on the development of tertiary dendrite arms is scarce in the literature. In the present study, the tip cooling rate, local solidification time, primary and tertiary dendrite arm spacings have been determined in Pb–Sb alloys castings directionally solidified under unsteady-state heat flow conditions. The alloys compositions experimentally examined are widely used in the as-cast condition for the manufacture of positive and negative grids of lead-acid batteries. The initial growth of tertiary dendritic arms from the secondary branches was found to occur only for a Pb–3.5 wt% Sb alloy at cooling rates in the range 0.4–0.2 K/s, with no evidence of this spacing pattern for Pb–Sb alloys having lower solute content. Tertiary dendritic branches have been observed along the entire casting lengths for alloys of the Pb–Sb hypoeutectic range having compositions higher than 4.0 wt% Sb. It is shown that a power function experimental law with a characteristic −0.55 exponent is able to characterize the tertiary spacing evolution with the solidification cooling rate for alloys compositions ≥4.0 wt% Sb. The only exception was the Pb–3.5 wt% Sb alloy for which λ3 exhibited significant lower values when compared with the experimental values obtained for the other Pb–Sb alloys for a same solidification cooling rate.

Research paper thumbnail of EIS and potentiodynamic polarization studies on immiscible monotectic Al–In alloys

Electrochimica Acta, 2013

Research paper thumbnail of The effect of melt temperature profile on the transient metal/mold heat transfer coefficient during solidification

Materials Science and Engineering: A, 2005

Research paper thumbnail of Investigation of intermetallics in hypoeutectic Al–Fe alloys by dissolution of the Al matrix

Intermetallics, 2009

During the non-equilibrium solidification typical of DC (direct chill) castings a range of coolin... more During the non-equilibrium solidification typical of DC (direct chill) castings a range of cooling rates occur from the surface to the casting center, and can cause the formation of metastable intermetallic phases (AlmFe, Al6Fe, etc.) in addition to the stable Al3Fe phase. The extensive presence of the plate-like Al3Fe phase in the as-cast structure adversely influences the mechanical properties of

Research paper thumbnail of Optimization of the zone melting of materials

Research paper thumbnail of Purification of iron and its magnetic properties characterization

Research paper thumbnail of Method of characterization of magnetic parameters in pure iron-carbon alloys

Research paper thumbnail of THE APPLICATION OF A NEW HEAT-FLOW MODEL TO PLANAR FREEZING IN STATIC AND CONTINUOUS-CASTING OF STEELS

Research paper thumbnail of Mathematical model for the unidirectional solidification of metals: II. Massive molds

Metallurgical Transactions B, 1979

Research paper thumbnail of Analytical technique for the determination of solidification rates during the inward freezing of cylinders

Journal of Materials Science, 1983

Research paper thumbnail of The application of a new solidification heat flow model to splat cooling

Journal of Materials Science, 1981

Research paper thumbnail of Control of the Directional Solidification of Aluminum-Copper Ingots

Research paper thumbnail of Heat Transfer Conditions of the Metal/Mold System Affecting the Refinement of the Silumin(Al-12 per cent Si) Solidification Structure

Research paper thumbnail of Calculation of the Time and Temperature Distribution in the Solidification of Nonferrous Metals. I.--Case of Water Cooled Molds

Research paper thumbnail of Heat Transfer in the Metal/Mold System in Refining the As-Cast Structures of Silumin(Al-12 per cent Si)

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