Advanced Engineering Materials

Cover image for Vol. 10 Issue 1‐2

February, 2008

Volume 10, Issue 1-2

Pages 3–142

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Editorial
    4. Contents
    5. Reviews
    6. Communications
    1. Cover Picture: Nano-characterization of Cast Structures by FIB-Tomography (Adv. Eng. Mater. 01-02/2008)

      F. Lasagni, A. Lasagni, M. Engstler, H. P. Degischer and F. Mücklich

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200890002

      Thumbnail image of graphical abstract

      In this communication, the three dimensional architectures of different Al-Si-(Mg) alloys are analyzed using SEM (Scanning Electron Microscopy)/FIB (Focus Ion Beam), EDS (Energy Dispersive Spectroscopy)/FIB and SEM-EDS/FIB tomographic methods. Several aspects for the imaging and quantification of the results are discussed describing the advantages and limitations of the methods to resolve submicron structures.

  2. Editorial

    1. Top of page
    2. Cover Picture
    3. Editorial
    4. Contents
    5. Reviews
    6. Communications
    1. Editorial Adv. Eng. Mater. 1-2/2008 (pages 3–4)

      J. Ritterbusch

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200890000

  3. Contents

    1. Top of page
    2. Cover Picture
    3. Editorial
    4. Contents
    5. Reviews
    6. Communications
  4. Reviews

    1. Top of page
    2. Cover Picture
    3. Editorial
    4. Contents
    5. Reviews
    6. Communications
    1. Effect of Hydrogen on the Mechanical Properties of Stainless Steels (pages 11–23)

      C. Borchers, T. Michler and A. Pundt

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700252

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      Fuel-cell vehicles running on hydrogen are planned to solve the long-standing problem of vehicular pollution. Hydrogen gas storage systems are one promising route, provided that a reliable and cheap material capable of withstanding hydrogen embrittlement is found. The physicochemical behaviour of stainless steel in the presence of hydrogen with special focus on a ductility minimum near room temperature is reviewed.

    2. Heterogeneous and Architectured Materials: A Possible Strategy for Design of Structural Materials (pages 24–36)

      O. Bouaziz, Y. Bréchet and J. D. Embury

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700289

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      Facing increasing demands for multifunctional solutions, the classical strategy of the metallurgist to improve properties, using microstructural refinement, reaches its limits: very often the function is not provided by the property only, but by the interplay between the shape, the properties, and possible association of materials. The purpose of the present paper is to outline new strategies for structural materials development offered by new degrees of freedom and by their combination: not only playing with the microstructure or with the macroscopic shape, but allowing a new scale for materials organization, the “architecture”, and controlling a new degree of freedom, the “spatial heterogeneity”. For these ideas to be effective, the question of processing such “heterogeneous architectured materials” in an affordable manner has to be kept in mind. Very often the development of architectured materials will require new processing methods.

  5. Communications

    1. Top of page
    2. Cover Picture
    3. Editorial
    4. Contents
    5. Reviews
    6. Communications
    1. Record Superplastic Ductility in a Magnesium Alloy Processed by Equal-Channel Angular Pressing (pages 37–40)

      R. B. Figueiredo and T. G. Langdon

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700315

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      The Mg-5.5 % Zn-0.5 % Zr alloy exhibits large superplastic elongations after processing by Equal-Channel Angular Pressing and these are strongly dependent on the number of passes through the die. Grain refinement improves the elongations up to a peak of ∼3050 % after 2 passes but grain growth limits ductility after larger numbers of passes.

    2. Bulk Nanostructured Cu with High Strength and Good Ductility (pages 41–45)

      H. Zhang, Z. Jiang, J. Lian and Q. Jiang

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700237

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      The tensile properties, deformation and fracture behavior of an electrodeposited Cu with an average grain size of ∼ 90 nm were investigated. Compared with other nanostructured Cu documented in the literature, this material exhibits a combination of high yield strength (356 MPa), good tensile elongation (18.2 %) and ductile fracture features. The persistence of work hardening at large strains and strain rate sensitivity might be responsible for the enhanced ductility.

    3. Iron Based Alloy with Hierarchical Structure and Superior Mechanical Performance (pages 46–50)

      J.-G. Wang, D.-Q. Zhao, M.-X. Pan and W.-H. Wang

      Version of Record online: 28 JAN 2008 | DOI: 10.1002/adem.200700253

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      The mechanical performances of Fe-based glass-forming alloys are improved by transcribing natural biological designs into the alloys. It is designed using a strategy of copious nucleation and high entropy of mixing, and prepared by simple casting method to obtain a hierarchical microstructure, which shows extraordinarily high strength and large ductility, high resistance to oxidation and corrosion. The strategy may serve as a design for development of structural materials.

    4. Bonding Low-density Nanoporous Metal Foams Using Sputtered Solder (pages 51–55)

      M. J. Bono, O. Cervantes, C. M. Akaba, A. V. Hamza, R. J. Foreman and N. E. Teslich

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700239

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      A method has been developed to bond low-density nanoporous copper foam components to an aluminum substrate using solder that is sputtered onto the surfaces. After assembling the components together and heating them to melt the solder, they were joined together by a layer of solder with a thickness of less than 2 μm.

    5. Simulation of Very High Temperature Overheating During Isothermal Creep of Single Crystal Ni-Base Superalloy (pages 56–61)

      J. Cormier, X. Milhet, J.-L. Champion and J. Mendez

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700248

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      This paper presents an experimental set-up developed for the simulation of overheatings under load representative of One Engine Inoperative events which can be encountered during in-service operation of turboshaft engines. These experiments provide several breakthroughs over classical testing equipments for the non-isothermal testing conditions of single crystal Ni-based superalloys. It was shown a major effect of thermal transition rates on the material behavior which was explained by microstructural evolutions.

    6. Nano-characterization of Cast Structures by FIB-Tomography (pages 62–66)

      F. Lasagni, A. Lasagni, M. Engstler, H. P. Degischer and F. Mücklich

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700249

      Thumbnail image of graphical abstract

      In this communication, the three dimensional architectures of different Al-Si-(Mg) alloys are analyzed using SEM (Scanning Electron Microscopy)/FIB (Focus Ion Beam), EDS (Energy Dispersive Spectroscopy)/FIB and SEM-EDS/FIB tomographic methods. Several aspects for the imaging and quantification of the results are discussed describing the advantages and limitations of the methods to resolve submicron structures.

    7. Martensitic Transformation in Ge2Sb2Te5 Alloy (pages 67–72)

      W. Zhang, H. S. Jeong and S. A. Song

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700230

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      Phenomenological crystallographic theory of martensitic transformation was applied to the phase transition of PRAM (phase-change random access memory) Ge2Sb2Te5 alloy for the first time. The speedy structural transition of Ge2Sb2Te5 from cubic to hexagonal phases could be well described by a shearing transformation from cubic {002} to hexagonal {-113} besides the removal of vacancies. This model shows good consistency with crystallographic models, X-ray diffraction analysis, ab initio total energy and density-functional theory calculations of Ge2Sb2Te5.

    8. In Situ Measurements of Local Strain in Heterogeneous Materials (pages 73–78)

      F. A. Lasagni, G. C. Requena and E. A. Soppa

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700250

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      In this study, the local deformation of an Al-7wt.% Si alloy, a 10 vol.% particle reinforced and 20 vol% short fibre reinforced metal matrix composites is studied. The strain field at the surface of the materials during tensile testing inside a scanning electron microscope is determined by image analysis and compared with FEM simulations.

    9. Multilayers Design for the Electromagnetic Sheet Metal Forming Die (pages 79–84)

      W. Tillmann and E. Vogli

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700212

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      To enhance the resistance of dies employing by EMB to wear and impact an innovative concept concerning the die surface modification was developed. Different PVD multilayer systems were deposited, in which the hardness and toughness of the layers were designed related to the soft aluminium sheets and high forming velocity. Corresponding metallographic and mechanical investigations of the multilayers help to understand the relation between microstructure and tribological properties.

    10. Subsurface Deformation After Dry Machining of Grade 2 Titanium (pages 85–88)

      M. S. Dargusch, M.-X. Zhang, S. Palanisamy, A. J. M. Buddery and D. H. StJohn

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700233

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      The effect of machining speed during dry machining of commercial purity titanium was investigated on the surface roughness, residual stress and depth of deformation along with changes in the microstructure of the deformed subsurface layer. Both optical analysis and TEM examination of the microstructure have shown (see the figure) that twining is a dominant mechanism of subsurface deformation during dry machining.

    11. Microstructure Characterization and Mechanical Properties of Linear Friction Welded Ti-6Al-4V Alloy (pages 89–92)

      W.-Y. Li, T. Ma, Y. Zhang, Q. Xu, J. Li, S. Yang and H. Liao

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700034

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      In this work, Ti-6Al-4V alloy was jointed by linear friction welding (LFW). A sound weld of thickness about 65–115 μm was obtained under the present processing parameters. The weld consisted of a superfine α + β microstructure, which is associated with the quick heating and cooling processes involved in LFW. This superfine microstructure contributes to the higher hardnesses of weld (422 ± 11Hv0.2) than that of parent Ti-6Al-4V (302 ± 20 Hv0.2). The tensile properties of weld are comparable to or higher than those of parent Ti-6Al-4V.

    12. Influence of Homogenization Annealing of AZ91 on Mechanical Properties and Corrosion Behavior (pages 93–103)

      M.-C. Zhao, M. Liu, G. L. Song and A. Atrens

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700234

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      A homogenization annealing (HA) heat treatment is proposed for property enhancement for AZ91; HA for 10 h at 410 °C caused an improvement in hardness, ultimate tensile strength and ductility without loss of corrosion properties. The influence on the corrosion behavior of the microstructure was studied.

    13. Influence of Microstructure on Corrosion of As-cast ZE41 (pages 104–111)

      M.-C. Zhao, M. Liu, G. L. Song and A. Atrens

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700246

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      Corrosion of ZE41 initiated in the α-Mg matrix adjacent to the eutectic micro-constituent and was attributed to micro-galvanic corrosion of the α-Mg matrix coupled to the eutectic micro-constituent. The eutectic micro-constituent did not act as a corrosion barrier and did not stop the advance of the corrosion. As a consequence, the α-Mg matrix corroded over the whole surface with little corrosion of the inter-connected eutectic micro-constituent.

    14. Deformation Limits in Shape-Memory Polymers (pages 112–119)

      C. M. Yakacki, S. Willis, C. Luders and K. Gall

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700184

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      This paper examines the link between polymer structure, temperature, and thermomechanics of shape-memory polymer networks. Strain to failure of the networks was extremely dependent on test temperature and reached a significant maximum near the onset of glass transition; a phenomenon denoted the deformability peak. A new protocol for maximizing stored strain in shape-memory polymers is presented and the results are discussed in regards to biomedical applications.

    15. Piezoelectricity of Cellular Polypropylene Films Expanded by a Dichlormethane Evaporation Process (pages 120–125)

      N. Behrendt, X. Zhang, B. Bergmann and G. M. Sessler

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700216

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      In this paper, a new method for expanding stretched cellular isotactic polypropylene (i-PP) is presented. Firstly, the cellular i-PP films with small cavities were saturated with dichlormethane (DCM) and then, the DCM was abruptly evaporated at elevated temperature to create large-cavity cellular films. Finally, the expanded film samples were quenched in liquid nitrogen to fix the cell structure. After corona charging, the piezoelectric d33-coefficients of such expanded films were measured by quasistatic and interferometric methods. The results show that the highest values of the quasistatic piezoelectric d33-coefficient of up to 2500 pC/N at low frequencies were observed on samples twice expanded with DCM. A high thermal stability of the piezoelectric activity was also observed. The high d33-values are due to the air escape sideways out of the large voids of the cellular films.

    16. Determination of Fiber Size Distributions of Injection Moulded Polypropylene/Natural Fibers Using X-ray Microtomography (pages 126–130)

      A. Alemdar, H. Zhang, M. Sain, G. Cescutti and J. Müssig

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700232

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      Microstructural analysis is of particular importance to understand the mechanical behaviour of short fiber reinforced composites. A non-destructive, high resolution X-ray microtomography (Micro-CT) technique was used to determine length, width and volume distributions of the wood and hemp fibers in polypropylene (PP) based composites. Results show that the use of the MAH-PP coupling agent decreased the fiber breakage in the composite considerably. Noticeable small width distribution and higher aspect ratio were obtained for the carded and enzyme separated hemp fibers.

    17. Multi-walled Carbon Nanotube-Reinforced Hydroxyapatite Layers on Ti6Al4V Medical Implants by Electrophoretic Deposition (EPD) (pages 131–138)

      C. Kaya, I. Singh and A. R. Boccaccini

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700241

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      Sol-gel synthesised nano-size hydroxyapatite (HA) powders were dispersed in water-based suspensions with the addition of multi-walled carbon nanotubes. Ti6Al4V medical alloys were coated with monolithic and carbon nanotube-reinforced HA using electrophoretic deposition (EPD) in an attempt to control deposit structure and thickness. It was shown that the sintering temperature of the deposited HA layers was significantly lowered by the use of sinter active nano-powders. Moreover the addition of carbon nanotubes increased the bonding strength of the EPD-formed layers to the metallic substrate. The cost-effective EPD technique used in the present work has high industrial potential for coating metallic medical implants with composite bioactive layers.

    18. Preparation and Thermophysical Properties of Sm2(Ce0.3Zr0.7)2O7 Ceramic (pages 139–142)

      H.-S. Zhang, Z.-J. Li, Q. Xu, F.-C. Wang and L. Liu

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adem.200700153

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      A doped rare earth zirconate Sm2(Zr0.7Ce0.3)2O7 for thermal barrier coatings was synthesized by solid reaction between La2O3,CeO2 and ZrO2 powders at 1600 °C for 10 hours. The phase composition and microstructure were analyzed by XRD and SEM respectively. And the linear thermal expansion coefficient and thermal conductivity were measured by pushing-rod method and laser-flash method. The analytic results indicated that a single phase Sm2(Zr0.7Ce0.3)2O7 with fluorite structure was synthesized and the microstructure was dense and no other phase existed among the particles. With the temperature increasing, the thermal expansion coefficient of the ceramic increased, while the thermal conductivity decreased.'The product had a higher thermal expansion coefficient as compared to Sm2Zr2O7 which fulfilled the requirement of thermal barrier coatings. Because the phase transformation from pyrochlore to fluorite, Sm2(Zr0.7Ce0.3)2O7 had a higher thermal conductivity than Sm2Zr2O7,but the thermal conductivity of synthesized ceramic was still much lower than that of 8YSZ. These results show that Sm2(Zr0.7Ce0.3)2O7 can be used as a novel candidate material for the ceramic layer in the new thermal barrier coatings system.

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