Grain Boundaries
Mostrando 13-24 de 87 artigos, teses e dissertações.
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13. Caracterización de soldaduras cuproaluminotérmica en cañerías de conducción para la protección catódica
ABSTRACT Copper-Aluminothermic weld is a process in which welder is generated by thermofusion. The necessary heat is obtained by the aluminum reducing effect above copper oxide, creating a high temperature exothermic reaction, in which melt and overheated copper is the filler material [1].This technique is used to joint rails in railway industry, in groundin
Matéria (Rio J.). Publicado em: 19/07/2018
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14. Evolución microestructural durante el envejecimiento a alta temperatura de una aleación 35Ni-25Cr-Nb
ABSTRACT The dendritic-type microstructure of the 35Ni-25Cr-Nb alloy, in the as-cast condition, consists of an austenitic matrix and two types of eutectic primary carbides; Nb-rich MC type and Cr-rich M23C6 type both presents in interdendritic edges and grain boundaries. During aging at 800ºC for different times, M23C6 type secondary carbides precipitate in
Matéria (Rio J.). Publicado em: 19/07/2018
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15. Influencia del tiempo de revenido a 780°C sobre la resistencia al creep del acero ASTM A335 P91
ABSTRACT It has been investigated the effect of tempering time at 780°C on the creep strength of ASTM A335 grade P91 steel. The tempering temperature corresponded to the industrial tempering temperature and the times evaluated were chosen in such a way to accumulate, between the tempering prior as received (40 min) and the treatment carried out in the labor
Matéria (Rio J.). Publicado em: 19/07/2018
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16. The Microstructure and Mechanical Properties of As-cast Mg-10Gd-3Y-xZn-0.6Zr (x = 0, 0.5, 1 and 2 wt%) Alloys
The microstructure, mechanical properties and fracture behavior of as-cast Mg-10Gd-3Y-xZn-0.6Zr (x = 0, 0.5, 1 and 2 wt%) alloys have been investigated by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and tensile tests. The experimental results reveal that the microstructure of the alloy without Zn contains α-Mg and Mg
Mat. Res.. Publicado em: 21/06/2018
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17. Low-Temperature Anelastic Property of Nanocrystalline Ag Fabricated by Gas Deposition Method
It was reported that the internal friction (Q-1) of nanocrystalline (n-) Au and n-Cu showed a rapid increase linearly with temperature above ~200 K. Since the rapid increase in Q-1 decreased with the progress in the grain growth, it was suggested that the anelasticity of grain boundaries in n-Au and n-Cu was thermally activated above ~200 K. In order to purs
Mat. Res.. Publicado em: 04/06/2018
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18. Carbon Distribution in Ferritic-Martensitic Fe-Cr-C Alloys
Carbon distribution in Fe-Cr-C alloys with a variety of Cr concentrations is studied based on internal friction, optical and transmission-electron microscopy. It is found that the carbon distribution strongly depends on initial microstructure, being ferritic or ferritic/martensitic, which is determined by the thermal treatment, and Cr and carbon concentratio
Mat. Res.. Publicado em: 28/05/2018
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19. Solution Treatment Behaviors of 6061 Aluminum Alloy Prepared by Powder Thixoforming
Powder thixoforming (PTF) was a promising processing technology that can be used to fabricate high strength particle reinforced aluminum matrix composites, and a pioneer 6061 matrix alloy was fabricated utilizing PTF to investigate its solution treatment behaviors. A comparison study with traditional permanent mold cast (PMC) 6061 alloy disclosed that PTF al
Mat. Res.. Publicado em: 07/05/2018
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20. Sunlight-driven water splitting using hematite nanorod photoelectrodes
ABSTRACT The efficiency of nanostructures for photoelectrochemical water-splitting is fundamentally governed by the capability of the surface to sustain the reaction without electron trapping or recombination by photogenerated holes. This brief review will summarize the latest progress on hematite, designed with columnar morphology via chemical synthesis, fo
An. Acad. Bras. Ciênc.. Publicado em: 2018
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21. Application of Friction Surfacing to the Production of Aluminum Coatings Reinforced with Al2O3 Particles
The aim of this work was to produce deposits of AA6351-T6, reinforced with alumina (Al2O3) particles, over a substrate of AA5052-H32 through friction surfacing. AA6351-T6 consumable rods were drilled with one and two holes, which were filled with Al2O3 particles posteriorly. To perform the deposition, a conventional KONE KFE-3/BR milling machine was used. Th
Mat. Res.. Publicado em: 13/11/2017
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22. Electrochemical Study of the AISI 409 Ferritic Stainless Steel: Passive Film Stability and Pitting Nucleation and Growth
The aim of the present work was to study the passive film stability and pitting corrosion behavior of the AISI 409 stainless steel. The electrochemical tests were carried out in 0.1 M NaCl solution at room temperature. The general electrochemical behavior was assessed using electrochemical impedance spectroscopy (EIS) measurements whereas the semiconducting
Mat. Res.. Publicado em: 18/09/2017
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23. Characterization of the Austenite Reformation Mechanisms as a Function of the Initial Ferritic State in a UNS S32304 Duplex Stainless Steel
Aiming to better understand the effects of heat treatment parameters on Ferrite-Austenite phase transformation in a 2304 duplex stainless steel different thermal cycles were applied to this steel in a quenching dilatometer. The obtained microstructures were characterized by optical microscopy, transmission electron microscopy and electron backscatter diffrac
Mat. Res.. Publicado em: 17/08/2017
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24. Microstructure Evolution of the Mg-5.8 Zn-0.5 Zr-1.0 Yb Alloy During Homogenization
The influence of homogenization treatment on microstructure evolution of Mg-5.8Zn-0.5Zr-1.0Yb (mass fraction, %) alloy was investigated under different annealing temperatures and holding times. Results indicated a severe dendritic segregation in the as-cast ingot. Zn and Yb segregate remarkably at the grain boundary and Zr appears in the form of precipitates
Mat. Res.. Publicado em: 08/06/2017