Advanced Engineering Materials

Cover image for Vol. 9 Issue 9

Special Issue: Magnesium Alloys and their Applications

September, 2007

Volume 9, Issue 9

Pages 723–821

Issue edited by: K. U. Kainer

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Contents
    4. International News
    5. Reviews
    6. Research News
    7. Communications
    8. Guide for Authors
  2. Contents

    1. Top of page
    2. Cover Picture
    3. Contents
    4. International News
    5. Reviews
    6. Research News
    7. Communications
    8. Guide for Authors
    1. Contents: Adv. Eng. Mater. 9/2007 (pages 723–726)

      Article first published online: 20 SEP 2007 | DOI: 10.1002/adem.200790027

  3. International News

    1. Top of page
    2. Cover Picture
    3. Contents
    4. International News
    5. Reviews
    6. Research News
    7. Communications
    8. Guide for Authors
    1. International News: Adv. Eng. Mater. 9/2007 (pages 727–729)

      Article first published online: 21 SEP 2007 | DOI: 10.1002/adem.200790029

  4. Reviews

    1. Top of page
    2. Cover Picture
    3. Contents
    4. International News
    5. Reviews
    6. Research News
    7. Communications
    8. Guide for Authors
    1. Thermodynamic Simulation of Phase Formation During Blending of Mg-Alloys by Thixomolding (pages 731–738)

      A. Kozlov, M. Djurdjevic and R. Schmid-Fetzer

      Article first published online: 20 SEP 2007 | DOI: 10.1002/adem.200700156

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      Thixomolding, as a semisolid processing approach, offers a unique opportunity to produce new Mg-alloys by mixing different feedstock chips at room temperature. This way of blending or mixing two or more commercially available standard Mg alloys will produce a new alloy with different melting range, solidification path, phase distribution and metallurgical and mechanical properties. This paper demonstrates the applicability of thermodynamic modeling to generate detailed information about phase formation in thixomolding process. For this purpose the process is pictured by appropriate thermodynamic calculations using a multicomponent Mg alloy database.

    2. A New Analytical Approach to Reveal the Mechanisms of Grain Refinement (pages 739–746)

      D. H. StJohn, P. Cao, M. Qian and M. A. Easton

      Article first published online: 20 SEP 2007 | DOI: 10.1002/adem.200700157

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      This paper presents an overview of a new methodology for investigating the grain refinement performance of alloys and master alloys and then uses this methodology to shed new light on the mechanisms occurring during superheating and native grain refinement, and the effect of iron and manganese on grain refinement in magnesium alloys. The methodology also describes changes in grain size upon Zr grain refinement of Mg and has been used to analyse the potential for the use of SiC to grain refine Mg-Al alloys. With this new methodology, and the knowledge it generates, the potential for the discovery of new or improved refiners is significantly enhanced.

  5. Research News

    1. Top of page
    2. Cover Picture
    3. Contents
    4. International News
    5. Reviews
    6. Research News
    7. Communications
    8. Guide for Authors
    1. Mechanical Properties and Environmental Behavior of a Magnesium Alloy with a Nano-/Sub-Micron Structure (pages 747–750)

      E. Aghion and A. Arnon

      Article first published online: 20 SEP 2007 | DOI: 10.1002/adem.200700142

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      Newly developed magnesium alloys with a consolidated nano/sub-micron structure and substantially higher specific strength may be considered as an interesting candidate for super-light high-strength applications. Consolidated nano/sub-micron structure applies to alloys with a combined microstructure of nano-crystalline and sub-micron grains. The aim of the present study was to explore the mechanical and environmental behavior of a consolidated nano/sub-micron magnesium alloy with the composition of AZ31.This was required in order to evaluate the applicability of this new structured alloy for practical applications.

    2. Development of Investment-Casting Process of Mg-Alloys for Aerospace Applications (pages 751–756)

      G. Arruebarrena, I. Hurtado, J. Väinölä, C. Cingi, S. Dévényi, J. Townsend, S. Mahmood, A. Wendt, K. Weiss and A. Ben-Dov

      Article first published online: 20 SEP 2007 | DOI: 10.1002/adem.200700154

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      Investment casting offers high-quality castings with good dimensional accuracy, being therefore suitable for aircraft applications. Since commercial ceramic shells react with Mg melts and appropriate inhibitors being not available, magnesium alloys are not widely used in industrial investment-casting. In order to overcome this situation and enable the aircraft industry to take advantage of the light-weight properties of magnesium, the process is analyzed within the European FP6 IDEA project, which aims at developing new high-strength magnesium casting alloys for aeronautic applications.

    3. Microstructural and Mechanical Behavior of Friction Welds in a High Creep Resistance Magnesium Alloy (pages 757–763)

      G. A. Pinheiro, C. A. W. Olea, J. F. dos Santos and K. U. Kainer

      Article first published online: 20 SEP 2007 | DOI: 10.1002/adem.200700159

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      Friction weldability of Mg based alloys has been worldwide discussed. Within this context the aim of this study was to investigate rotational friction welding of an Aluminum-Rare Earth based high creep resistance Mg alloy AE42HP from the viewpoint of thermo cycle-microstructure-performance relationships to evaluate the potential use of FW in joining modern Mg-alloys.

    4. Mg Based Bulk Metallic Glasses with high Mechanical Strength and Large Viscoplastic Forming Capacity (pages 764–768)

      S. Puech, J. J. Blandin and J. L. Soubeyroux

      Article first published online: 20 SEP 2007 | DOI: 10.1002/adem.200700160

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      Mg based BMGs appear of special interest since they can provide new light alloys for structural applications with net shape fabrication possibilities. A large number of studies have been carried out to find good glass former compositions for Mg alloys. Frequently, Mg-Cu-RE compositions have been selected. In the present work, various compositions close to the Mg65Cu25Gd10 one are investigated. The resulting mechanical properties at room temperature are studied and a particular attention is also given to the deformation capacity of theses alloys in their glass transition interval

  6. Communications

    1. Top of page
    2. Cover Picture
    3. Contents
    4. International News
    5. Reviews
    6. Research News
    7. Communications
    8. Guide for Authors
    1. Advancements in High Pressure Die Casting of Magnesium (pages 769–776)

      H. Gjestland and H. Westengen

      Article first published online: 20 SEP 2007 | DOI: 10.1002/adem.200700168

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      The high pressure die casting (HPDC) process is characterized by rapid die filling and a subsequent rapid cooling of the molten metal. These characteristics are favourable for magnesium die casting alloys. Due to the high cooling rate the microstructure formed reveals a fine dendrite and grain structure, which in turn leads to substantial hardening and improved ductility. Hydro Competence Centre for Magnesium has studied the HPDC process in a 420 tons die casting machine dedicated for research work. In the present paper the correlation between the thermal conditions through the process and the resulting microstructure and the mechanical properties in the casting is discussed. The effect of vacuum assisted die filling will also be discussed.

    2. Analysis of Superplastic Deformation of AZ31 Magnesium Alloy (pages 777–783)

      F. K. Abu-Farha and M. K. Khraisheh

      Article first published online: 20 SEP 2007 | DOI: 10.1002/adem.200700155

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      AZ31 is a magnesium alloy possessing good mechanical properties, which makes it particularly attractive for automotive applications. Yet, in order to advance the utilization of this alloy, a broad database of its superplastic behavior is needed. This work presents the results of a comprehensive study on the elevated temperature superplastic behavior of the AZ31 magnesium alloy. Flow stress, fracture strain and strain sensitivity index maps were constructed over a wide range of strain rates, covering temperatures between 325 and 450 °C.

    3. The Effect of Zinc and Gadolinium on the Precipitation Sequence and Quench Sensitivity of Four Mg-Nd-Gd alloys (pages 784–792)

      L. R. Gill, G. W. Lorimer and P. Lyon

      Article first published online: 20 SEP 2007 | DOI: 10.1002/adem.200700158

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      A study has been carried out on the effects of zinc and gadolinium concentration on the microstructure, properties and quench sensitivity of four alloys of similar composition to the commercial magnesium alloy Elektron 21. Increasing the gadolinium content of the alloys produced enhanced solid-solution strengthening which inproved the strength of the alloy in all heat treated conditions. Increasing the zinc content increased the quench sensitivity of the alloys. The quench rate from the solution treatment temperature had a significant affect on the precipitates formed during subsequent ageing.

    4. Elektron 21 – An Aerospace Magnesium Alloy for Sand Cast and Investment Cast Applications (pages 793–798)

      P. Lyon, I. Syed and S. Heaney

      Article first published online: 20 SEP 2007 | DOI: 10.1002/adem.200700165

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      The majority of work done with Elektron 21 has been for sand cast applications. Investment casting, is a means of reducing wall thickness (and hence weight) of complex components. This process is generally restricted to small components for Magnesium due to metal mould reaction. Use of low reactivity Elektron 21 gave successful results during investment casting (using plaster and shell moulds). Using improved processing technology, it has been shown that large components can be made successfully in this alloy with out reaction. This opens new opportunities for further weight reduction in weight sensitive applications.

    5. Micro-Alloyed Wrought Magnesium for Room-Temperature Forming (pages 799–802)

      F. O. Riemelmoser, M. Kühlein, H. Kilian, M. Kettner, A. C. Hänzi and P. J. Uggowitzer

      Article first published online: 20 SEP 2007 | DOI: 10.1002/adem.200700161

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      In this work the development of a system of micro-alloyed Mg–Ag–Ca–Mn–(Zr) alloys is described. It involves grain refinement throughout the production chain of direct chill casting and extrusion. After extrusion the alloys reveal a homogeneous microstructure and a fine grain size of less than 10 μm. At room temperature they show an exceptionally high elongation to fracture – of more than 25 % – and a pronounced work hardening regime. Superplastic behaviour is observed at 360 °C.

    6. Forming of Magnesium – Crystal Plasticity and Plastic Potentials (pages 803–806)

      S. Graff, D. Steglich and W. Brocks

      Article first published online: 20 SEP 2007 | DOI: 10.1002/adem.200700162

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      Magnesium alloys show a deformation behaviour, which is quite different from that of other lightweight materials like aluminium. What constitutes the difference is the respective crystalline structure, namely hexagonal close-packed (hcp) for magnesium and face-centred cubic (fcc) for aluminium. Capturing the special features of the deformation phenomena of magnesium hence requires accounting for the microstructural mechanisms. This is realised with the help of crystal plasticity. The specific slip mechanisms occurring in magnesium are identified and single crystals as well as textured polycrystals are analysed numerically. The linking of micro- and mesoscale provides a procedure for the simulation of the yielding and hardening behaviour of arbitrarily textured solids with hcp structure.

    7. Tensile-Compressive Creep Asymmetry of Recent Die Cast Magnesium Alloys (pages 807–812)

      S. Xu, M. A. Gharghouri and M. Sahoo

      Article first published online: 20 SEP 2007 | DOI: 10.1002/adem.200700163

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      The tensile-compressive creep asymmetry of die cast magnesium alloys is experimentally explored and the possible deformation mechanisms are discussed. Creep tests were performed under tension and compression at 125 °C and 150 °C on die cast Mg alloys AM50, AE44 and AJ62A. Higher tensile than compressive creep strengths were observed for all alloys except for low pressure die cast AM50 at a low creep stress of 35 MPa at 125 °C. An aging treatment of 250 hours at 180 °C was employed for AM50 samples to obtain an over-aged microstructure that would minimize the effects of dynamic precipitation of β-Mg17Al12 on creep. The creep data for the aged samples showed significant scatter, and the trend in tensile-compressive creep asymmetry of the aged samples is not clear for the short-term creep tests under high creep stresses.

    8. The InnMag Project – Processing Mg for Civil Aircraft Application (pages 813–819)

      M. Kettner, U. Noster, H. Kilian, R. Gradinger, W. Kühlein, A. Drevenstedt, F. Stadler, E. Ladstaetter and A. Lutz

      Article first published online: 20 SEP 2007 | DOI: 10.1002/adem.200700143

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      In the context of the “InnMag” project, partners from industry and science are co-operating to investigate the issues involved in adapting established production processes to the material Mg. The project's aim is to further the deployment of Mg interior parts in civil aircraft. The project covers every production step, from alloy selection, Mg ingot melting, alloying, direct chill casting, extruding, machining, surface treatment and component assembly. This paper discusses the project's targets and the results arrived at so far, particularly in the areas of direct chill casting and extrusion.

  7. Guide for Authors

    1. Top of page
    2. Cover Picture
    3. Contents
    4. International News
    5. Reviews
    6. Research News
    7. Communications
    8. Guide for Authors
    1. Guide for Authors: Adv. Eng. Mater. 9/2007 (page 821)

      Article first published online: 21 SEP 2007 | DOI: 10.1002/adem.200790030

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