Advanced Engineering Materials

Cover image for Vol. 7 Issue 8

August, 2005

Volume 7, Issue 8

Pages 649–770

    1. Cover Picture: An Investigation of the Inelastic Deformation of Cortical Bone (Adv. Eng. Mater. 8/2005)

      C. Mercer, R. Wang and A. G. Evans

      Version of Record online: 16 AUG 2005 | DOI: 10.1002/adem.200590015

      Failure in bovine cortical bone in flexure is compression dominated, as indicated by higher peak stresses but lower failure strain (than in tension), and shear bands on the compression surfaces of the specimens. Cyclic unloading-reloading revealed significant hysteresis. Strains achieved upon cycling were significantly higher than the failure strains under monotonic loading. The breaking and reformation of sacrificial bonds is the proposed explanation of this “healing” phenomenon.

    2. Contents: Adv. Eng. Mater. 8/2005 (pages 649–652)

      Version of Record online: 16 AUG 2005 | DOI: 10.1002/adem.200590014

    3. A Critical Review of the Stress Corrosion Cracking (SCC) of Magnesium Alloys (pages 659–693)

      N. Winzer, A. Atrens, G. Song, E. Ghali, W. Dietzel, K. U. Kainer, N. Hort and C. Blawert

      Version of Record online: 16 AUG 2005 | DOI: 10.1002/adem.200500071

      This review aims to provide a foundation for the safe and effective use of magnesium (Mg) alloys, in support for the rapidly increasing use of Mg in industrial applications, particularly in the automobile industry. Included are recommendations for preventing SCC of Mg alloys exposed to the atmosphere or aqueous solutions. An important recommendation is that the total stress in service should be below a threshold level, which could be ∼ 50% of the tensile yield strength.

    4. Micro-Raman Studies on DLC coatings (pages 694–705)

      G. Irmer and A. Dorner-Reisel

      Version of Record online: 16 AUG 2005 | DOI: 10.1002/adem.200500006

      Raman scattering is an excellent tool to characterize nanocrystalline clusters and the structural arrangement of carbon atoms in carbon-based materials. Diamond-like carbon (DLC) films are used in many industrial applications due to their hardness, wear resistance and biological compatibility. The properties of DLC coatings depend on the carbon coordination and incorporation of other elements, influences onto their Raman spectra will be reviewed.

    5. Small-Amplitude Atomic Force Microscopy (pages 707–712)

      S. V. Patil and P. M. Hoffmann

      Version of Record online: 16 AUG 2005 | DOI: 10.1002/adem.200500054

      Small amplitude Atomic Force Microscopy (AFM) is a new AFM technique developed to perform linear measurements of nanomechanical phenomena. Using ultra-small cantilever amplitudes and very high sensitivity deflection sensors, this technique has been used to measure atomic and molecular forces and dynamics on clean crystalline surfaces as well as in liquids. Atomic resolution imaging of force gradients and linear measurements of atomic bond stiffnesses are just one application.

    6. Quantitative Elastic-Property Measurements at the Nanoscale with Atomic Force Acoustic Microscopy (pages 713–718)

      D. C. Hurley, M. Kopycinska-Müller, A. B. Kos and R. H. Geiss

      Version of Record online: 16 AUG 2005 | DOI: 10.1002/adem.200500039

      We are developing metrology for rapid, quantitative assessment of elastic properties with nanoscale spatial resolution. Atomic force acoustic microscopy (AFAM) examines the resonant vibrations of an atomic force microscope (AFM) cantilever in contact with a material. AFAM provides measurements of modulus at either a fixed sample position or as a map of local property distributions. The information obtained furthers our understanding of nanopatterned surfaces, thin films, and nanoscale structures.

    7. An Investigation of the Inelastic Deformation of Cortical Bone (pages 719–723)

      C. Mercer, R. Wang and A. G. Evans

      Version of Record online: 16 AUG 2005 | DOI: 10.1002/adem.200500078

      Failure in bovine cortical bone in flexure is compression dominated, as indicated by higher peak stresses but lower failure strain (than in tension), and shear bands on the compression surfaces of the specimens. Cyclic unloading-reloading revealed significant hysteresis. Strains achieved upon cycling were significantly higher than the failure strains under monotonic loading. The breaking and reformation of sacrificial bonds is the proposed explanation of this “healing” phenomenon.

    8. The Relationship between Grain Boundary Character and the Intergranular Oxide Distribution in IN718 Superalloy (pages 723–726)

      S. L. Yang, U. Krupp, H.-J. Christ and V. Braz Trindade

      Version of Record online: 16 AUG 2005 | DOI: 10.1002/adem.200500036

      The relationship between grain boundary character and the intergranular oxide distribution was investigated on the polycrystalline nickel-base superalloy IN718 by using EBSD technique. Basically, internal oxidation predominantly occurs along random grain boundaries, while, for highly symmetric grain boundaries, such as Σ3 twin grain boundaries, intergranular oxides were rarely found.

    9. Investigation of Thixoforged Damper Brackets made of the Steel Grades HS6-5-3 and 100Cr6 (pages 726–735)

      W. Püttgen, W. Bleck, I. Seidl, R. Kopp and C. Bertrand

      Version of Record online: 16 AUG 2005 | DOI: 10.1002/adem.200500026

      The suitability of a variety of different steel grades for semi-solid processing was investigated by means of differential thermal analysis, quenching experiments, metallographic investigations, line scan technology and hardness measurements. Thixoforging trials with the promising steel grades 100Cr6 and HS6-5-3 were used to validate the suitability of both steel grades by manufacturing the structural component “damper bracket”. The microstructures of these steels during thixoforging differ significantly: The grade HS6-5-3 develops a homogeneous and fine globulitic grain distribution with mainly liquid phase at the grain boundaries; the grade 100Cr6 develops a coarse grained microstructure with high entrapped liquid contents beside the intergranular liquid. The experience with laboratory processed components can be summarized that either the production of geometrically complex components (homogenous, fine globulitic structure) or the production with a determined microstructure and property gradients (coarse-grained structure) are possible.

    10. Influence of Particulate Reinforcements on the Damping Behavior of Magnesium (pages 735–743)

      N. Srikanth, S. Ugandhar, M. Gupta and T. S. Srivatsan

      Version of Record online: 16 AUG 2005 | DOI: 10.1002/adem.200500041

      The properties of magnesium, specifically the specific stiffness, strength and damping, can be enhanced by the addition of reinforcements such as silicon carbide particulates. This paper highlights the results of a study aimed at investigating the possible variation in overall damping property, measured using an impact based vibration method coupled with circle-fit approach, which focuses on the internal friction arising at the matrix-reinforcement particulate interfaces. The study also examines the intrinsic influence of a second reinforcing phase, which is particulate of titanium, along with particulates of silicon carbide.

    11. Biomorphous SiSiC/Al-Si Ceramic Composites Manufactured by Squeeze Casting: Microstructure and Mechanical Properties (pages 743–746)

      C. Zollfrank, N. Travitzky, H. Sieber, T. Selchert and P. Greil

      Version of Record online: 16 AUG 2005 | DOI: 10.1002/adem.200500087

      SiSiC/Al-Si composites were fabricated by pressure-assisted infiltration of an Al-Si alloy into porous biocarbon preforms derived from the rattan palm. Al-Si alloy was found in the pore channels of the biomorphous SiSiC preform, whereas SiC and carbon were present in the struts. The formation of a detrimental Al4C3-phase was not observed in the composites. A bending strength of 200 MPa was measured. The fractured surfaces showed pull-out of the Al-alloy.

    12. Preparation of Dense Mullite Ceramics through Gelcasting of Alumina Slurry Dispersed in Silica Sol (pages 746–750)

      Deyu Kong, Si'ai Ying, Hui Yang, Hui Li, Su Wei and Jiabang Wang

      Version of Record online: 16 AUG 2005 | DOI: 10.1002/adem.200400142

      A nano-SiO2-coated-Al2O3 (NSCA) micro-composite system has been derived from silica sol and alumina to prepare dense mullite ceramics by gelcasting technology. Concentrated NSCA suspension with high solid loading but low viscosity was successfully prepared, utilizing the stabilization mechanism of silica nanoparticle halos around alumina particles at pH 9.5. The defect-free dried green body with bending strength of 5.85 MPa was obtained with only 7.7 wt.% of monomer and dense mullite ceramics was sintered at 1550°C for 2 h, through initial densification by transient viscous sintering, followed by a densification arrest and then a further densification by solid-state diffusion at higher temperatures.

    13. Statistical Analysis of Experimental Parameters in Selective Laser Sintering (pages 750–755)

      J.-P. Kruth and S. Kumar

      Version of Record online: 16 AUG 2005 | DOI: 10.1002/adem.200500030

      Selective Laser Sintering (SLS) is one of the rapid manufacturing processes which promises to manufacture products not only out of polymer powders but also from metals and ceramics. In an SLS experiment carried out by taking iron-based powders, the analysis of the effects of parameters Scan Speed, Layer Thickness and Scan Spacing has been done by measuring the responses density, hardness and surface roughness.

    14. Database and Selection Method for Portable Power Sources (pages 755–765)

      L. Fu, T. J. Lu and J. E. Huber

      Version of Record online: 16 AUG 2005 | DOI: 10.1002/adem.200500037

      A method for selecting power sources including batteries, fuel cells and solar cells is developed. It is based on matching the physical and performance characteristics of power sources, such as weight, volume, capacity, voltage and cost, to the requirements of the given task. Physical and performance characteristics are collated from manufacturers' data and a database is built using advanced selection software. This allows the construction of performance maps in terms of voltage, maximum current, mass energy density, volume energy density and cost, giving a systematic comparison of different kinds of power sources. The use of the method as a preliminary design tool is demonstrated in a case study on the selection of batteries for mobile phones.

    15. Mat-DB: A Web-Enabled Materials Database to Support European R&D Projects and Network Activities (pages 766–770)

      H. H. Over, E. Wolfart, W. Dietz and L. Toth

      Version of Record online: 16 AUG 2005 | DOI: 10.1002/adem.200500059

      Fast access to product specific materials data is one of the challenges in materials technology in order to make full use of the available materials potential. Material databases in combination with the Internet are powerful means to address this issue. The Joint Research Centre of the European Commission at Petten, The Netherlands (JRC) has recently launched the web-enabled Mat-DB for experimentally measured data, which is based on many years of experience in this field. Furthermore, the JRC aims at creating a growing pool of publicly available materials data and analysis routines, which can be used in industry, research and education.

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