E. Bedolla
Universidad Michoacana de San Nicolás de Hidalgo
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Featured researches published by E. Bedolla.
Scripta Materialia | 2003
A. Contreras; C.A. León; R. A. L. Drew; E. Bedolla
The wetting of TiC by liquid aluminum and magnesium under static argon between 800 and 1000 C is studied using the sessile drop technique. Extensive interfacial reaction occurs between Al and TiC, leading to the formation of aluminum carbide; conversely no reaction occurs for Mg/TiC. 2003 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing | 2000
A. Albiter; C.A León; R. A. L. Drew; E. Bedolla
Abstract Composites of a commercial Al-2024 alloy reinforced with particulate TiC have been produced by the pressureless melt infiltration route. Infiltration was carried out at 1200°C for 2 h and composite materials containing 52 and 55 vol.% TiC were obtained. The phases other than the matrix and the reinforcement were identified as CuAl2, AlTi3, Ti3AlC, and TiAl3. It was found that the composites were age hardenable after solutionizing at 530°C for 150 min and subsequent natural or artificial ageing at 190°C. Mechanical properties of the composites, as-fabricated and heat-treated, showed a strong dependency on the ceramic content. After heat treatment, the 55% TiC composites showed an increase of hardness from 28.5 to 38.5 HRC; meanwhile ultimate tensile strength increased from 379 to 480 MPa. A similar behavior, as a function of heat treatment, was observed for the composites containing 52% TiC, but the estimated values were lower than those obtained for the 55% TiC composites. Scanning electron microscope (SEM) examination revealed transgranular fracture throughout the CuAl2 agglomerated precipitates in the as-fabricated composites. In the heat-treated conditions, brittle and intergranular fractures were observed.
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing | 2002
A Albiter; E. Bedolla; R. Pérez
The microstructure and chemical characteristics of nanocrystalline NiAl intermetallic phase with a B2 crystalline structure are studied. Nanophase NiAl powder with the addition of minor elements (Fe, Ga and Mo) was prepared by mechanical alloying under argon atmosphere. Structural characterization based on X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) observations were carried out on the NiAl compounds. The effects of the different microalloyed elements on the microstructure are explored.
Materials and Manufacturing Processes | 2000
A. Contreras; C.A León; R. A. L. Drew; E. Bedolla
Abstract A study of the infiltration process of several alloys (Al-2024, Al-6061, and Al-7075) into preforms of TiC was carried out. The preforms were sintered for one hour under argon at 1250,1350, and 1450°C with the aim of achieving different levels of densification. Using a thermogravimetric analyzer (TGA), infiltration profiles were obtained by continuously monitoring the weight change of preforms partially immersed in molten aluminum. Infiltration was carried out at different temperatures (ranging from 900 to 1200°C) under argon to evaluate infiltration kinetics. The infiltration rate of the aluminum into the preforms followed parabolic behavior and the activation energy changed according to the extent of preform densification. Average activation energies of 74, 99, and 138 k J mol−1 were obtained for the Al-7075, Al-6061, and Al-2024 alloys, respectively. Prior to infiltration, an incubation period was observed and its length depended on the temperature; lower the infiltration temperature, longer was the incubation period.
International Journal of Mineral Processing | 1990
Francisco J. Tavera; E. Bedolla
Abstract Equilibrium distributions of Cu, S, O and minor elements between silica-saturated fayalite slag, copper matte (44 to 79.5% Cu) and copper have been examined experimentally under controlled partial pressures of SO 2 , S 2 and O 2 . The temperature range of the experiments was 1473–1573K. Concentrations of copper in the experimental slags were found to be lower than 1% Cu as long as the matte grade was kept below 65% Cu; however, copper in the slag increases dramatically when matte grade is increased above this level. This is in accordance with previous observations. Concentrations of As, Sb, Bi, Pb and Cd in each liquid phase increased as matte grade was increased; experiments have shown that under high oxygen partial pressures minor elements are removed in the slag, whereas as oxygen pressure is decreased, these elements are removed into the gas phase.
Materials Science Forum | 2006
C.A. León; Y. Arroyo; E. Bedolla; E.A. Aguilar; R. A. L. Drew
A novel ceramic-metal composite with continuous interconnected ceramic and metal phases has been fabricated from sintered porous particulate AlN preforms infiltrated with magnesium. The 48 vol. % AlN composites are fabricated by pressureless infiltration in argon in the temperature range of 870 °C to 960 °C. An increase in the infiltration rate is observed as the temperature increases. Results on the mechanical characterization of the composites indicate an elastic modulus of 90 to 110 GPa and hardness of 70 to 80 HRB. The tensile strength calculated by the shear punch test method ranges from 260 to 390 MPa. As a general rule, it is observed that the lower the infiltration temperature, the higher the tensile strength. The linear coefficient of thermal expansion of the infiltrated composites in the temperature range of 215 to 315 °C is 7.65 x 10-6 °C-1. This value is lower than those found for similar Al/AlN composites reported in the literature.
Composite Interfaces | 2017
A. Reyes; E. Bedolla; R. Pérez; A. Contreras
Abstract Mg-AZ91E/TiCp composite was fabricated using a spontaneous infiltration technique at 950 °C under an argon atmosphere. The composites produced have 37 vol.% of metal matrix and 63 vol.% of TiC-like reinforcement. The obtained composites were subsequently solution heat-treated at 413 °C during 24 h, cold water quenched, and subsequently artificially aged at 168 and 216 °C during 16 h in an argon atmosphere. Effect of heat treatment on the microstructure and mechanical properties was evaluated. Microstructural characterization was analyzed using different techniques such as X-ray diffraction (XRD) and scanning electron microscopy (SEM). Interface between matrix and reinforcement was examined using transmission electron microscopy (TEM), and mechanical properties were evaluated by measuring the elastic modulus and hardness. Mg, TiC, Al, and Mg17Al12 phases through XRD were detected. Meanwhile, using TEM analysis in heat-treated composites MgAl2O4, MgO, and Al2O3 were identified. The as-fabricated composite have elastic modulus and hardness of 162 GPa and 316 Hv, respectively. After solution heat treatment and aging at 168 °C during 12 h, the composites reaches values of 178 GPa and 362 Hv for the elastic modulus and hardness, respectively. Time of aging was correlated with measures of elastic modulus and hardness.
Materials Science Forum | 2003
Victor H. López; C.A. León; Andrew R. Kennedy; R. A. L. Drew; E. Bedolla
The contact angle data drawn from sessile drop tests of commercial aluminum alloys (1010, 2024, 6061 and 7075) on TiC substrates (at 900 °C, under vacuum and argon atmospheres) was plotted on a logarithmic time scale. Several aspects were taken into account to describe the spreading mechanism in four kinetic stages in systems that exhibited wetting (1010, 2024 in both environments and 7075 under vacuum). It was found that commercial multi-element alloys do not improve wetting of Al on TiC and that alloying elements and the atmosphere exert a significant role on the wetting behavior in the early stages. A physical model describing spreading in the early stages is presented. The influence of alloying elements and the type of atmosphere on the deoxidation of the drops are discussed.
Materials Science Forum | 2013
Julieta Alonso-Santos; Mercedes G. Téllez-Arias; E. Bedolla; José Lemus-Ruiz
The objective of this work was to study various aspects of liquid state diffusion bonding of cylindrical samples of Al2O3 and commercially pure niobium (99.7%) by brazing using a 25 µm thick 70Cu-30Zn (wt%) alloy as joining element. Initially, sintering of alumina powder was carried out in order to produce a 7 mm diameter samples at 1550°C by 120 minutes. Joining experiments were carried out on Al2O3/Cu-Zn/Nb/Cu-Zn/Al2O3 sandwich-like combinations at temperature of 920°C, 950°C and 980°C using different holding times under argon (Ar) atmosphere. The experimental results show a successful joining of alumina to niobium at 950°C and 980°C, however not at 920°C. Joining of Al2O3/Cu-Zn/Nb/Cu-Zn/Al2O3 occurred by the formation of a homogeneous diffusion zone with no interfacial cracking or porosity at the interface. Scanning electron microscopy (SEM) micrographs show the layer formed in the reaction zone. It was observed that the width of the reaction zone increases with bonding temperature and time. Electron probe microanalysis (EPMA) revealed that at any particular bonding temperature, Nb travel into the Cu-Zn joining element forming a circular precipitate phase near to the alumina ceramic.
Acta Materialia | 2004
A. Contreras; E. Bedolla; R. Pérez