DOC

SYMPOSIUM E

By Jacqueline Campbell,2014-06-17 02:57
6 views 0
SYMPOSIUM E ...

    SBPMat

     BRAZIL-MRS

    nd

    2 Brazilian MRS Meeting

    October 26-29, 2003

    Symposium D:

    Structure Alloys for Transport Systems

    Symposium Organizers:____________________________________________________

    Ayrton Filleti (ABAL)

    David Wilkinson (Center for Automotive Materials, Canada)

    Guillermo Solórzano (PUC-Rio, SBPMat)

     1

    INVITED PRESENTATIONS

    D-I1 THERMOMECHANICAL PROCESSING OF STRIP CAST ALUMINUM ALLOYS FOR

    AUTOMOTIVE APPLICATIONS

    D.S. Wilkinson, McMaster Centre for Automotive Materials, McMaster University, Department

    of Materials Science and Engineering, Ontario, Canada.

The McMaster Centre for Automotive Materials at McMaster is engaged in a wide ranging study

    of the processing of aluminum alloy sheet via strip casting. This ranges from a study of the solidification process through thermomechanical process of the cast product and the subsequent

    formability of the sheet. The current status of this research will be reviewed with particular

    emphasis on microstructure development during rolling recrystallization.

    D-I2 COMPACTED GRAPHITE IRON A NEW MATERIAL FOR DIESEL ENGINES

    CYLINDER BLOCKS AND CYLINDER HEADS

    W.L. Guesser Tupy Fundições and UDESC (Universidade do Estado de Santa Catarina) - wguesser@tupy.com.br Rua Albano Schmidt, 3400 Joinville SC, Brazil.

Emissions legislation and the demand for higher performance from smaller engines have together

    driven the development of diesel engine technology over the past ten years. The irreversible trend toward higher peak firing pressures has prompted engine designers to seek stronger materials in

    order to meet their targets without increasing the size or weight of their engines. With at least

    75% increase in ultimate tensile strength, 35-40% increase in elastic modulus and approximately

    double the fatigue strength of gray cast iron, compacted graphite iron (CGI) is ideally suited to

    meet the current and future requirements of diesel engine design. The paper provides an overview

    of the properties of CGI and the process control requirements for the production and control of

    low nodularity CGI microstructures and without the risk of flake graphite formation. Product

    results are provided for twenty different automotive castings, produced in a Brazilian foundry plant.

    D-I3 TEXTURE & SURFACE ROUGHENING IN ALUMINUM AUTOBODY SHEET A.D. Rollet, Y.S. Choi and H.R. Piehler; Department of Materials Science & Engineering,

    Carnegie Mellon University, Pittsburgh, PA 15213, USA

This paper will review the status of our understanding of texture and anisotropy in aluminum alloys

    used for lightweight autobodies. The main focus will be on the development of surface roughness

    during plastic deformation which can be a limiting factor in the application of such materials. Plastic interactions between specific neighboring grains are central to the formation of meso-scale surface roughening.

    As an example, meso-scale surface roughening in 6022-T4 Al sheets was investigated using plane-strain tension. The formation of grain-scale hills and valleys and their relation to the morphologies and

    corresponding orientations of surface grains after deformation was analyzed using various approaches

    based on the Schmid and Taylor crystal plasticity models. Surface grains with and without slip bands tended to form valleys and hills, respectively, wherever these two types of grains were adjacent to each

    other along the plane-strain tension direction. For samples pulled parallel to the transverse direction,

    the formation of hills and valleys by unbanded and banded grains was more lineally organized in the

    plane-strain (rolling) direction than for samples that were pulled parallel to the rolling direction. Slip

    banding and valley formation were observed mainly in the surface grains with either very few slip systems of high Schmid factors or low Taylor factors, in contrast to non slip-banded and hillforming surface grains. Quantitative analysis using correlation coefficients showed that the Schmid factor

    provided slightly better agreement than the Taylor factor in predicting slip-banding (an valley-forming) and non slip-banding (and hill-forming) behaviors of surface grains. In addition, image quality in

    Electron Back Scattered Diffraction (EBSD) from selected surface grains suggested that the slip-banded and valley-forming grains contain less lattice distortion than the non slip-banded and hill-forming grains despite the larger strains experienced by these grains. This indicates that dislocations in

    the slip-banded grains move out of the surface to create deformation without lattice distortion.

     2

    D-I4 THIXOFORMING OF Al ALLOYS SHAPPING THE FUTURE M.H. Robert; Mechanical Engineering Faculty, State University of Campinas, Campinas,

    CEP13083-970, SP, Brazil.

     Forming processes, in spite of their wide range of commercial application in countless techniques for

    shaping metallic products, can be sometimes restrict due to technical and economical reasons. In

    manufacturing processes such as casting, the high temperatures required impose restriction in the range of materials suitable for casting operations; on the other hand, mechanical forming processes, like

    forging, extrusion and drawing, where fully solid raw material is used, can be restrict to materials with

    high plasticity.

    Thixoforming can be the answer to these limitations: the use of semi-solid raw material with thixotropic flow behaviour can make it feasible the forming by casting at lower temperatures and by

    mechanical processes at lower pressures.

    Due to its thixotropy, semi-solid rheo or thixocast alloys can be handled as solid, even when containing

    relatively high liquid fraction; and present low resistance to deformation and flow under pressure, even

    containing high solid fraction. Moreover, present laminar flow when filling moulds. These characteristics make the thixotropic slurry suitable both for pressure casting processes and mechanical

    forming, with advantages over conventional processes where fully liquid or fully solid raw material is

    used.

    In casting processes, high quality, free of porosity products can be achieved with lower energy

    requirements, since casting temperatures can be significantly reduced (also with enormous

    consequence in die life).

    In mechanical forming processes, high quality, near net shape products can be achieved at reduced costs due to lower pressures required. More complex parts, using far simpler dies can be produced at

    lower costs and higher productivity. Reported results also show the possibility of using ceramic dies in

    mechanical forming operations when thixotropic slurries are employed. This work presents the basics of semi-solid processing (SSM or SSP) technology and obtained results

    on development of forming processes using thixotropic slurries of some ferrous and non-ferrous alloys, mainly Al alloys.

    D-I5 STRUCTURAL ALUMINUM ALLOYS FOR THE TRANSPORTATION MARKET

    SEGMENT

    A.S. Molero; Qualitat Consultoria Ltda., São Paulo, SP, Brasil.

Aluminum is a fantastic material. In fact, aluminum is a huge group of thousands of different

    materials, each one of them keeping most of the basic properties of the metal and improving one

    or more desired properties.

    Our presentation will focus on structural aluminum alloys for extrusion. Extrusion is a fantastic process as well. It is widely know, flexible and cheap. A good extrusion designer may create unbelievable shapes that may make viable many applications. Brazilian primary aluminum industry started in the second half of years 40. At the beginning of

    years 50 the first extrusion press was installed. Since then many other presses have been installed and the country has been more or less updated with the international technology involved with the

    utilization of aluminum alloy extrusions in various market segments, including transportation.

    Unfortunately, because of different reasons, we cannot say that a single application was well

    accepted by the market. Many companies follow investing in the development of applications is

    various market sub-segments, like auto parts, bus bodies, truck bodies, rail cars, bicycles and

    others.

    Major worldwide aluminum companies, like Alcoa, Alcan and Hydro keep their development

    centers in North America and Europe. So that, aluminum alloys utilized in transportation

    equipment are not developed in Brazil, but most of the alloys utilized around the world are available in Brazil.

    Most frequently utilized material is 6061-T6, a heat-treated medium strength Al-Mg-Si alloy

    developed many years ago. It is widely know by designers and extruders, easy to extrude

    (including hollow shapes) and presents mechanical properties similar to those ones of “common

    steel”.

    More “sophisticated” alloys are the ones that include Zinc, the 7XXX group, utilized in the

    aeronautical industry.

     3

    D-I6 ADVANCED MODELING TOOLS AND THE DEVELOPMENT OF STEELS FOR

    TRANSPORT SYSTEMS

    A.Costa e Silva, EEIMVR-UFF, Volta Redonda and IBQN, Av. Gen Justo 365/4 CEP20021-130, Rio de Janeiro, Brasil.

Several materials challenge the position of steel as the dominant material in automotive

    applications since the last decades of the last century. Although the participation of steel in this

    industry measured in weight fraction might have decreased, the participation expressed as a

    fraction of the material cost has been maintained. This is due, in large part, to the fact that steel

    design and processing has suffered significant development and advancement in the last decades.

    From the materials engineering point of view this represents a significant accomplishment in

    special considering the complexity of the steels currently in use and the cost constrains under which they must be produced to be competitive.

    We argue that the significant development in simulation, modeling and computational tools was

    crucial in making possible the achievement of the current state of steel design and process advancement. In this presentation, some of these tools and their applications are highlighted, with

    examples as well as consideration of their advantages and limitations. The current challenges in steel development, the strategies proposed to face some of these challenges as well as the tools that are becoming available are also discussed.

    D-I7 NANOMATERIALS FOR COOLING SOLUTIONS

    F.Fagotti and H.Fischer, EMBRACO S.A. Rua Rui Barbosa, 1020 Bl. 26, CEP89219-901, Joinville, SC, Brasil

Embraco S.A. invests in promising and innovative research projects that create growth for the

    refrigeration related business segments. We are seeking for research institutes/ researches with

    innovative solutions that will make a significant impact on the market. Our products and services are used for vital functions in homes, at workplaces and in public buildings in fact in virtually every human environment. We are a leading producer of refrigerating compressors in general but

    our product portfolio includes refrigeration and air conditioning controls, refrigerator thermostats

    and solutions to the global refrigeration and air conditioning industry. Embraco S.A. has about 9,200 employees worldwide, modern factories on three continents, and

    sales companies and representatives in more than 49 countries.

    Our main research focuses are:

    Extremely hard and wear resistant coatings and solid lubricants;

    Porous structures with high surface/ volume ratios and low gas flow resistance; Solid state refrigeration (thermoionic, thermoelectric, eletrocaloric and magnetocaloric) with high

    performance, mainly for room temperature applications;

    Materials with local improvements of strength or heat transfer related properties; Materials with anisotropic physical properties;

    Polymeric coatings for electrical/thermal/chemical insulation purposes.

     4

    D-I8 STEEL VERSUS OTHER MATERIALS IN THE AUTOMOTIVE INDUSTRY Gerard Maeder; Renault SAS, France.

    Worldwide, 45 million cars were made in 2002. Since a car weights a little over a tonne on avarage, that makes about 45 million tonnes of materials. Clearly, the automotive industry

    represents an exceptional market, not only for companies that produce machine for forming,

    protecting and assembling materials. Market opportunity gives rise to technical, economic and marketing rivalry among materials vendors, with each making its own claims to suremacy. One result of rivalry is a vastly increased breadth of choice, which can appear confusing to

    engineers and designers. And the rivalry can be fierce between advocates of steel, advocates of

    aluminium, advocates of polymers and composite materials.

    The automotive engineer will wish to examine this extended materials offer to seek optimum

    solutions to shifting vehicle specifications, which envolve with market pressure, customer

     emissions). expectations and regulatory constraints (especially safety and CO2This context of constant change has stimulated studies aimed at introducing alternativies to steel

    in various automotive applications. In many cases, alternative-material solutions will have been developed in other industries first, only crossing over to the automotive industry once cost and

    volume-production problems have been overcome.

    In this presentation I shall start with an overview of the current situation regarding materials use in the automobile industry, then go on to discuss factors that affect the choice of materials.

    Finally, I shall attempt the difficult exercise of forecastibg the future of steel alongside its

    emerging rivals.

    D-I9 CURRENT AND POTENCIAL APPLICATIONS OF MAGNESIUM ALLOYS IN

    AUTOMOTIVE INDUSTRY

    Fernando C.V.França, Technical Director, Diecasting Division, Rima Industrial .

    Magnesium is the lightest of the structural metals. As such, it forms the basis for commercial alloys that have found successful use in a wide variety of applications. Development of new

    generation of magnesium alloys and weight reduction for automotive fuel economy have pushed

    the growth of magnesium consumption in automotive industry at annual rate of 15% over the last decade. This impressive growth is predicted to continue at an annual rate of at least 9% for the

    next ten years.

    Despite the recent strong growth, the average amount of magnesium in vehicles is still very low,

    around 2,0 kg/vehicle. The content of magnesium in a typical family car is only 0,2% of the total

    vehicle weight, against 8,0% of aluminum content. Many authors have indicated that global

    automotive applications of magnesium could reach an average over 30 kg/vehicle within next 30 years.

    This paper summarizes the mechanical and physical properties of typical cast and wrought

    magnesium alloys in comparison with other competing materials, describes the present

    applications of different magnesium alloys in the automotive industry and discusses the developments of new creep-resistant magnesium alloys for powertrain applications. Finally the paper indicates some challenges that magnesium industry and research organizations

    must overcome in order to achieve high volume usage in ground transportation.

     5

    ORAL PRESENTATIONS

    D-O1 STUDY OF THE BEHAVIOR TO ABRASIVE WEAR IN PLANE SPECIMENS OF

    POLYURETHANE IN CONTACT WITH SPHERE OF GLASS AND AISI 52100 STEEL A.A.R. da Silva; M.M. Cabral; H.C. Villasanti, Mechanical Engineering Department, Federal University of Rio G. Norte UFRN- Natal- RN, Brazil; J.T.N. de Medeiros, Mechanical

    Engineering Department, Federal University of Rio G. Norte UFRN- Natal- RN, Brazil.

The aim of this investigation is to discuss the sliding wear among polyurethane specimens with

    spheres of glass (diameter ? = 17,8 ? 0,4 mm) and AISI 52100 steel (? = 12,7 ? 0,05 mm) specimens, interposing sand river in the interface. Weight loss, result of the relative movement

    between solids under load, deteriorate the contact and reduce, slow and catastrophically, the

    specimens lives. With the increase of the damage, the entropy production rate floats and the

    system requires more energy for its work. This type of study uses often tribomers, which has high

    costs. This work consisted in the development of a experimental setup to assay plane-sphere geometry with the nominal speed of 0.27 m/s and normal loads of 1 and 10 N. New and wearing

    surfaces were weighted and analyzed using optical and scanning electron microscopy (SEM). Characteristics wear damages by delaminating, microabrasion, formation of prow, fragile fracture

    and Schallamach waves were observed on the contact track of the polymer. It was determinated

    the wear rate for each one of the load conditions and this was compared with the foreseen values

    of LIU and LI [2001] and Archard [1952] equations. It was verified that: 1) the setup presented results with good repetitivity, 2) wear mechanisms transitions were identified and 3) a new model

    can be proposed to the assayed materials and conditions.

    D-O2 WARM FORMING FOR 7050-T76511 ALLOYS

    O.R.A. da Cruz, Empresa Brasileira de Aeoronáutica S.A., Av. Brigadeiro Faria Lima, 2170,

    CEP12227-901, São José dos Campos, Brasil; P.R. Costa Jr., Empresa Brasileira de Aeoronáutica S.A., Av. Brigadeiro Faria Lima, 2170, CEP12227-901, São José dos Campos, Brasil

The purpose of this study is to introduce the Warm Forming process as well as to present the

    mechanical properties and microstructure of the material under this forming process. In this process, the forming in a final heat treatment condition is allowable, avoiding a solution

    heat treatment before forming and an artificial aging after forming.

    The Warm designation is used due the temperature in which the forming process is carried out. The forming temperature is below the maximum temperature of the artificial aging and the

    heating do not cause loss of mechanical properties as tensile strength, yield strength, hardness and

    fatigue resistance.

    This process is used to form joggles in extruded profiles. These profiles, with structural functions

    are used to assembly aircraft fuselages.

    The operation uses CNC command, inductive heating and have a rigid control of the thermal

    cycle.

     6

    D-O3 INFLUENCE OF SHORT DEFECTS IN THE AUTOMOTIVE COMPONENT BEHAVIOR

    (STABILIZER BAR) UNDER CYCLIC LOADS

    M.A. Colosio, General Motors do Brasil, Engenharia de Materiais, Av. Do Estado 2880,

    CEP09501-970, São C. do Sul, Brasil; A.H.P. Andrade, Instituto de Pesquisas Energéticas e

    Nucleares IPEN, Departamento de Materiais, Trav. R400, Cidade Universitária SP, CEP05508-000, São Paulo, SP, Brasil.

Constantly designer and engineer are challenged to project components with high performance,

    low weigh and long life, but with reasonable cost during a short time and moreover, always

    thinking about fatigue problem.

    In order to overcome that, the advantage study in material fatigue has been made on the research

    field that did was not so important at few years ago, as i.e. short cracks and surface residual stresses.

    The objective of the present paper, applied in SAE5160 steel, is to seek a quantitative evaluation

    of defects physically small (about 300?m) and carry out torsional (R= -1) and axial (R = 0,1) fatigue tests using stabilizer bar and cylindrical specimens with and without shot peening. This evaluation is shown by fatigue life reduction, fractographic studies on fracture face and

    crack metallographies.

    At this study, the proposal methods have the difficult task to contribute to ample vision of short defect presence on component and specimen surfaces, which are originated from manufacturing

    process or in using.

     7

    POSTER PRESENTATIONS

    D-P1 EFFECT OF THE ATMOSPHERE IN CREEP OF TI-6Al-4V ALLOY. D.A.P. Reis, M.C.A. Nono, Instituto Nacional de Pesquisas Espaciais, LAS, São José dos Campos, 12201-970, Brazil. F. Piorino, C.R.M. Silva, Centro Técnico Aeroespacial, IAE, São

    José dos Campos,12228-904, Brazil. M.J.R. Barboza, Faculdade de Engenharia Química de Lorena, DEMAR, 12600-000 Lorena, Brazil. E.B.Taddei, Centro Técnico Aeroespacial, ITA, São

    José dos Campos, 12228-904, Brazil. danieli@las.inpe.br

    The search for alloys with improved high-temperature specific strength and creep-resistance properties for aerospace applications has led in the last decades to sustained research activities to

    develop new alloys and/or improve existing ones. A substantial part of these activities has been

    devoted to titanium alloys, due to their high strength-to-weight ratio [1]. The high strength and low density of titanium and its alloys have from the first ensured a positive role for the metal in

    aero-engine and airframe applications. Its difficult to imagine how current levels of performance,

    engine power to weight ratios; airframe strength; aircraft speed and range and other critical

    factors could be achieved without titanium [2]. Ti-6Al-4V is currently used in aeronautic and

    aerospace industry mainly for applications that require resistance at high temperature such as, blades for aircraft turbines and steam turbine blades [3]. The titanium affinity by oxygen is one of

    main factors that limit the application of their alloys as structural materials at high temperatures

    [4-5]. Notables advances have been obeserved in the development of titanium alloys with the

    objective of improving the specific high temperature strength and creep-resistance properties. However, the surface oxidation limits the use of these alloys in temperatures up to 600ºC [6]. The objective of this work was estimate the influence of the atmosphere in creep of the Ti-6Al-4V alloy. It was produced cylindrical specimens to creep test and tested at 600ºC in nitrogen and

    air atmospheres using stress of 125, 222, 250 and 319 MPa. When the Ti-6Al-4V was tested in nitrogen atmosphere the effect of the oxidation was smaller and the behavior of the creep curves

    showed that the life time was better in atmosphere not so oxidant, there was an increasing of

    ductility of material (final strain) and life time. Occurred a decreasing of steady state creep in

    function of the reduction of oxidation process, showing that for the Ti-6Al-4V alloy their life time was strongly affected by the atmosphere that was submitted because the oxidation suffered by the

    material.

    D-P2 ASPECTS OF CREEP BEHAVIOUR OF ALUMINIUM ALLOY RR- 58 UNDER STRESS VARIATION AT 180ºC.

    L. O. Bueno, Universidade Federal de São Carlos / DEMA, Rod.W.Luiz,km.235, 13565-905 SãoCarlos(SP), Brazil.

    The Hiduminium RR-58 alloy was chosen for the manufacture of the airframe of Concorde supersonic aircraft which due to kinetic heating is subjected to a creep environment during

    service. This work reports some aspects of creep deformation observed at 180ºC with different

    kinds of stress variations carried out on the material during creep tests involving the primary,

    secondary and tertiary stages. Correlations are found for primary creep and secondary creep stage

    parameters and also for the initial creep rate and the secondary creep rate in each cycle of stress

    variation. The strain transient behaviour after different amount of stress decrements during

    secondary creep is also observed, with careful examination for the presence of incubation periods

    and anelastic effects. The occurrence of anelastic creep for large stress decrements is followed and some correlation is noticed between the creep strain rate monitored just before the stress

    variation and the initial anelastic creep rate following the stress reduction. Anelastic creep

    builds up during primary, secondary and tertiary creep deformation. As the stress cycling period

    is decreased there is evidence that the creep strain may be all recoverable.

     8

    D-P3 ANELASTIC CREEP BEHAVIOUR OF RR-58 ALUMINIUM ALLOY AT 180?C. L. O. Bueno, Universidade Federal de São Carlos / DEMA, Rod.W.Luiz,km.235, 13565-905

    SãoCarlos(SP), Brazil.

    The strain relaxation behaviour after full stress removals during creep of RR-58 aluminium alloy has been observed. This alloy has been chosen in the 1960s for the manufacture of the

    supersonic Concorde airframe. Tensile creep tests were carried out at 180ºC, with stresses of 120,

    170 and 230 MPa. Specimens were subjected to a series of unloading cycles after different creep

    time periods involving the primary and the secondary creep stages. In all tests strain relaxation was measured until its virtual saturation. At least two stages of relaxation were observed: the

    first one of short duration followed by the second one operating at slower decreasing strain

    rates. For stress removals performed during primary creep, only the fast stage is revealed. When

    secondary creep is established the second relaxation stage begins to operate, apparently in parallel

    with the first stage. Attempts were made to interpret the results according to a model based on

    thermally activated dislocation kinetics for unbowing of dislocation segments, as proposed in the

    literature in the past. A suggestion for modification is made to the model, considering a more

    realistic behaviour of the dislocation links during unbowing after stress removal during creep

    D-P4 TEXTURE AND MICROTEXTURE STUDIES IN DIFFERENT TYPES OF CAST IRONS M. F. de Campos, L. C. Rolim Lopes, P. Magina; Escola de Engenharia Industrial Metalúrgica de

    Volta Redonda / Universidade Federal Fluminense, Av. dos Trabalhadores 420 - Vila Santa Cecília - CEP 27255-125, Volta Redonda, RJ, BRASIL; C. T. Kunioshi, H. Goldenstein, Depto.

    Metalurgia e Materiais, Escola Politecnica da Universidade de São Paulo.

Cast irons are classified according the different morphologies assumed by the graphite. The three

    main types are gray cast iron, vermicular/compacted graphite cast iron, and spheroidal or nodular

    cast iron. In the present study, the microstructure of cast irons belonging to the three above

    mentioned classes were extensively characterized in a SEM Scanning Electron Microscope equipped with of EBSD Electron Back Scattered Diffraction Patterns. The microstructure of

    these different cast irons are compared, relating the microstructural features to the mechanical

    properties. Differences about the morphologies of perlite found in those three types of cast irons

    are also discussed. The microtexture was evaluated by means of EBSD. The macrotexture was

    determined in a X-ray diffractometer with texture goniometer. The analysis of texture suggests random distribution of the orientations of ferrite grains, a consequence of the process of

    production, that includes steps as solidification (first giving origin to austenite), and subsequent

    transformation of austenite into ferrite, after cooling.

    D-P5 IN SITU OBSERVATION BY TEM OF CRYSTALLINE DEFECTS AND PRECIPITATE

    INTERACTIONS IN AN AL-MG-ZR ALLOY

    A.Almeida Filho, S.J. Buso, W.A. Monteiro CCTM Instituto de Pesquisas Energéticas e Nucleares, Travessa R. 400, 05508-900

The interaction processes among crystalline and precipitate defects are of fundamental interest in

    the recovery and recrystalization processes in metallic alloys. Materials, such the aluminum

    alloys, when at high deformation degrees, create an amount of crystalline defects that provide them certain mechanical properties. The analysis of the degree of crystalline defects is, in many

    cases, indirectly observed, through mechanical test, such as microhardness analysis. However, the

    direct observation allows the visualization of the mechanisms involved besides allowing the

    evaluation and comparison of data obtained with theoretical models. The objective of this work is the in situ observation by transmission electron microscopy of the

    interaction of crystalline defects and precipitate in samples of an Al-Mg-Zr alloy, produced by powder metallurgy, cold deformed (79% of reduction in area), without previous thermal

    treatment, in hot stage system, coupled to the TEM JEOL JEM 200C, available in CCTM of

    IPEN/USP.

     9

    D-P6 CHARACTERIZATION BY TEM OF AN AL-MG-TH ALLOY PRODUCED BY POWDER

    METALLURGY

    A.Almeida Filho, S.J. Buso, W.A. Monteiro CCTM Instituto de Pesquisas Energéticas e

    Nucleares, Travessa R. 400, 05508-900

In the last decade, light materials have been studied thoroughly and used in components of pieces

    in the industries: automobile, naval and aerospacial. Their application makes possible: to reduce

    the mass, to increase the load capacity, increase of the speed and, when there is possibility, to

    improve the mechanical properties. Among those materials, the aluminum alloys have

    prominence special, due not only to the lightness of the material, but also to certain mechanical

    properties and the reciclability. Starting from the decade of 1930, aloys of magnesium were developed containing thorium, with the objective of improvement of the mechanical properties

    and creep resistance. The development of these alloys didn't present progress during about twenty

    years, after which the need of materials for nuclear applications did with that magnesium - thorium woke up interest.

    Alloys produced by powder metallurgy have as main characteristics: homogeneity in the

    microstructure and chemical composition, besides low size of grains. In this process it is possible

    to elevate the amounts of elements, that have low solubility, around 5 times your maximum

    solubility in liquid.

    This work has as objective the characterization transmission electron microscopy of an Al-2Mg-1Th alloy, produced by powder metallurgy and submitted to cold deformation processes and

    annealing.

    D-P7 STRUCTURAL AND MAGNETIC PROPERTIES OF DISORDERED FE-CU-MN ALLOYS W. E. Pöttker, J. A. Valcanover, Faculdades Reunidas de Administração, Ciências Contábeis e

    Econômicas de Palmas, FACEPAL, Palmas, CEP 35500-000, PR, Brasil; C. Paduani, Departamento de Física, Universidade Federal de Santa Catarina, UFSC, Florianópolis, CEP

    88040-900, SC, Brasil; F. França, Departamento de Física, UDESC, Joinville, SC, Brasil; J.

    D. Ardisson, Centro de Desenvolvimento da Tecnologia Nuclear, CDTN, Belo Horizonte, CEP

    30123-970, MG, Brasil; M. I. Yoschida, Departamento de Química, Universidade Federal de

    Minas Gerais, ICEX-UFMG, Belo Horizonte, Caixa Postal 702, CEP 31270-901, MG, Brasil.

    In this work we investigate the formation and stabilization of ternary disordered Fe-Mn-Cu alloys. Although Fe and Cu are practically imiscible, the addition of Mn leads to the formation of

    ternary alloys with single phase The samples are prepared by arc melting under argon atmosphere and are analyzed with several experimental techniques, as X-ray diffraction, thermogravimetry, Mössbauer effect at room temperature and at liquid nitrogen temperature. The analysis of the

    difractograms indicates that a single bcc phase is observed in the iron rich alloys, which present a

    ferromagnetic phase at room temperature as verified by the Mössbauer spectroscopy

    measurements. We investigate the effect of the copper concentration in the stabilization and on

    the magnetic behavior of the bcc phase in these alloys.

     10

Report this document

For any questions or suggestions please email
cust-service@docsford.com