Advanced Engineering Materials

Cover image for Advanced Engineering Materials

December, 2004

Volume 6, Issue 12

Pages 925–1003

    1. Contents: Adv. Eng. Mater. 12/2004 (pages 925–928)

      Article first published online: 17 DEC 2004 | DOI: 10.1002/adem.200490010

    2. Coupled Thermo-Mechanical Analysis of Severe Plastic Deformation for Producing Bulk Nanostructured Materials (pages 933–936)

      Q.X. Pei, C. Lu and M.W. Fu

      Article first published online: 9 DEC 2004 | DOI: 10.1002/adem.200400100

      In recent years, bulk nanostructured materials produced by methods of severe plastic deformation have attracted growing research interest. This article presents a coupled thermo-mechanical finite element analysis of the severe plastic deformation in the workpiece materials during equal channel angular pressing (ECAP) to optimize the ECAP process and the die design.

    3. Premium 7075 Aluminium Alloys Produced by Reciprocating Extrusion (pages 936–943)

      S.-W. Lee, J.-W. Yeh and Y.-S. Liao

      Article first published online: 9 DEC 2004 | DOI: 10.1002/adem.200400107

      Reciprocating extrusion is a novel method to refine the grains and inclusions of 7075 Al alloy. The reciprocatingly extruded 7075-T6 alloys exhibit superior strength-toughness combinations to conventional 7000 series alloys. Their available yield strength used in unstable crack growth condition can reach up to 550 MPa. The improved mechanisms in microstructure and properties are discussed.

    4. Microstructure and Strengthening Mechanism of Oxide Lanthanum Dispersion Strengthened Molybdenum Alloy (pages 943–948)

      G.-J. Zhang, Y.-J. Sun, R.-M. Niu, J. Sun, J.-F. Wei, B.-H. Zhao and L.-X. Yang

      Article first published online: 9 DEC 2004 | DOI: 10.1002/adem.200400072

      The strength of molybdenum alloys dispersed by different mass fraction oxide lanthanum particles has been determined at room temperature and related to the microstructure. It was found that fine oxide lanthanum particles incur a fine grain size and contribute much to the alloys strength. The quantitative relationships between the strengths of the alloys and the sizes, volume fraction of oxide lanthanum particles and the grain sizes were presented.

    5. An Mg-Al-Zn Alloy with Verry High Specific Strength and Superior High-strain-rate Superplasticity Processed by Reciprocating Extrusion (pages 948–952)

      S.-W. Lee, H.-Y. Wang, Y.-L. Chen, J.-W. Yeh and C.-F. Yang

      Article first published online: 9 DEC 2004 | DOI: 10.1002/adem.200400117

      A novel method called “Reciprocating Extrusion” is exploited to realize the high potential of Mg-15Al-1Zn alloy to exhibit superior mechanical properties and superplasticity, bypassing the costly and complicated RS+PM route. Such refined alloys exhibit unique high-strain-rate superplasticity at 325 °C and maximum elongation larger than 1610% at 1×10–2 s–1. They also possess greater strength/density than 7075-T736 Al alloys.

    6. Simulation of Solid State Sintering through FE Modeling for the Optimum Design of 3D Parts (pages 952–957)

      D. Vallauri and G. Maizza

      Article first published online: 9 DEC 2004 | DOI: 10.1002/adem.200400104

      Modelling of sintering provides an effective assisting tool for process optimisation and accurate design of near net shape parts. In this paper the shrinkage and shape changes of 3D real components are simulated during solid-state sintering through a combination of a multi-physics microscopic model and a macroscopic FE model. The computed stress and temperature fields allow for prediction of sinter distortions with the aim of minimising them and help in manufacturing of near net shape parts. The model results are in good agreement with literature data.

    7. Enhancing the Properties of Magnesium using SiC Particulates in Sub-micron Length Scale (pages 957–964)

      S.U. Reddy, N. Srikanth, M. Gupta and S.K. Sinha

      Article first published online: 9 DEC 2004 | DOI: 10.1002/adem.200400105

      A novel method of Disintegrated Melt Deposition technique (see Figure) was used to synthesize the magnesium composites containing sub-micron size SiC particulates. The enhanced mechanical and thermal properties are attributed to the uniform distribution of sub-micron size SiC particulates and good SiC-Mg interfacial integrity. The results revealed that SiC particulates in submicron length scale are superior in improving overall properties of magnesium when compared to SiC particulates in micron length scale.

    8. Synthesis and Low Cycle Fatigue Behavior of In-situ Al-based Composite Reinforced with Submicron TiB2 and TiC Particulates (pages 964–968)

      S.C. Tjong and G. Wang

      Article first published online: 9 DEC 2004 | DOI: 10.1002/adem.200400099

      Low cycle fatigue behavior of in-situ aluminum based composite reinforced with submicron TiB2 and TiC particulates was investigated. This novel composite was prepared from the TiO2-Al-B-C system via reactive hot pressing. The incorporation of carbon into such a system induces the formation of TiC particulate at the expense of brittle Al3Ti phase. The influence of submicron particulate formation on the tensile and fatigue properties of the composite is discussed.

    9. Ni-YSZ Graded Coatings Produced by Dipping (pages 969–971)

      B. Ferrari and R. Moreno

      Article first published online: 9 DEC 2004 | DOI: 10.1002/adem.200400116

      A new colloidal processing route for the shaping of a graded Ni-YSZ composite for applications in SOFC devices is described. A Ni foil is coated by Ni/YSZ layers by dipping in aqueous suspensions with an organic binder. Behind the metal-ceramic layers introduced to improve adhesion, an outer thin layer of nanosized YSZ is formed by electrophoretic deposition.

    10. Electrical Discharges under High Voltage on Surface of Silica-Nickel Ceramic Composites (pages 972–976)

      A. Jankowiak and P. Blanchart

      Article first published online: 9 DEC 2004 | DOI: 10.1002/adem.200400120

      Strong electrical breakdowns on surface of Silica-Nickel cermets are obtained under pulsed electric field. The electric field is significantly lower than for breakdowns at a similar air gap under the same atmosphere pressure. This hot plasma-like process can be used for gas or liquid ignition. Processes follow the Paschen's and the Fowler-Nordheim's laws at surface micro-protrusions, when the current percolates through the composite material.

    11. Reaction in the Al-TiO2-CB4 System and in Situ Synthesis of an Al/(TiC+TiB2+α-Al2O3) Composite (pages 977–980)

      Z. Wang, X. Liu and X. Bian

      Article first published online: 9 DEC 2004 | DOI: 10.1002/adem.200400041

      Differential scanning calorimeter, X-ray diffraction and thermodynamic analysis results show that the Al-TiO2-CB4 mixture can react in the Al matrix to form TiC, TiB2, and α-Al2O3 phases between 860 and 1040 °C according to the following equation: 4 Al + 3 TiO2 + CB4 = TiC + 2 TiB2 + 2 α-Al2O3. Using this reaction system, an Al/(TiC + TiB2 + α-Al2O3) composite was in situ synthesized successfully in molten aluminum heated by middle-frequency induction furnace.

    12. Micron-scale Deformation and Damage Mechanisms of Ti3SiC2 Crystals Induced by Indentation (pages 980–983)

      Z.-F. Zhang, Z.-M. Sun, H. Zhang and H. Hashimoto

      Article first published online: 9 DEC 2004 | DOI: 10.1002/adem.200400071

      Vickers hardness, deformation and damage mechanisms of Ti3SiC2 crystals induced by indentation in the load range of 0.25 – 20 N were investigated. The Vickers hardness of Ti3SiC2 crystals decreases with increasing indentation load and finally reaches a constant value of ∼ 4 GPa. The typical deformation and damage modes in Ti3SiC2 crystals include: sliding, buckling, kinking, delamination and cleavage fracture of deformation bands as well as intergranular cracking. A deformation and damage mechanism map for Ti3SiC2 crystals was summarized.

    13. Structure-Processibility Relationships During Rotational Moulding of Plastics (pages 983–992)

      A. Tcharkhtchi and J. Verdu

      Article first published online: 9 DEC 2004 | DOI: 10.1002/adem.200400126

      During the rotational moulding of plastics there are a number of key temperatures that influence to a large extent the production of good quality parts. Using well established relationships between the structure and processibility of plastics, this paper explains why polyethylene is much easier to process by rotational moulding than other polymers such as polyamides, poly(ethylene terephtalate), poly(vinylchloride) or polypropylene.

    14. Author Index 2004 (pages 993–995)

      Article first published online: 17 DEC 2004 | DOI: 10.1002/adem.200490011

    15. Subject Index 2004 (pages 996–1003)

      Article first published online: 17 DEC 2004 | DOI: 10.1002/adem.200490012