Tungsten foil laminate for structural divertor applications – Joining of tungsten foils

Abstract This paper is the fourth in our series on tungsten laminates. The aim of this paper is to discuss laminate synthesis, meaning the joining of tungsten foils. It is obvious that the properties of the tungsten laminate strongly depend on the combination of (i) interlayer and (ii) joining technology, as this combination defines (i) the condition of the tungsten foil after joining (as-received or recrystallised) as well as (ii) the characteristics of the interface between the tungsten foil and the interlayer (wettability or diffusion leading to a solid solution or the formation of intermetallics). From the example of tungsten laminates joined by brazing with (i) an eutectic silver copper brazing filler, (ii) copper, (iii) titanium, and (iv) zirconium, the microstructure will be discussed, with special focus on the interface. Based on our assumptions of the mechanism of the extraordinary ductility of tungsten foil we present three syntheses strategies and make recommendations for the synthesis of high temperature tungsten laminates.

[1]  T. Höschen,et al.  Feasibility Study of a Tungsten Wire Reinforced Tungsten Matrix Composite with ZrOx Interfacial Coatings , 2010 .

[2]  G. Leichtfried,et al.  On the 45° embrittlement of tungsten sheets , 1995 .

[3]  Masayoshi Kawai,et al.  Development of re-crystallized W–1.1%TiC with enhanced room-temperature ductility and radiation performance , 2010 .

[4]  P. Rao,et al.  Phase Diagrams of Binary Tungsten Alloys , 1991 .

[5]  Said I. Abdel-Khalik,et al.  Recent US activities on advanced He-cooled W-alloy divertor concepts for fusion power plants , 2011 .

[6]  O. Kraft.  Crystalline materials: Twin behaviour and size. , 2010, Nature materials.

[7]  Michael Rieth,et al.  Tungsten foil laminate for structural divertor applications – Basics and outlook , 2012 .

[8]  T. Höschen,et al.  Interfacial fracture behavior of tungsten wire/tungsten matrix composites with copper-coated interfaces , 2010 .

[9]  A. Seeger.  Peierls barriers, kinks, and flow stress: Recent progress , 2002 .

[10]  D. Brunner.  Comparison of Flow-Stress Measurements on High-Purity Tungsten Single Crystals with the Kink-Pair Theory , 2000 .

[11]  W. Schubert,et al.  Tungsten: Properties, Chemistry, Technology of the Element, Alloys, and Chemical Compounds , 1999 .

[12]  J. Koike.  Dislocation Plasticity and Complementary Deformation Mechanisms in Polycrystalline Mg Alloys , 2004 .

[13]  Michael Rieth,et al.  Influence of microstructure and notch fabrication on impact bending properties of tungsten materials , 2010 .

[14]  Stephen Roberts,et al.  An empirical correlation between temperature and activation energy for brittle-to-ductile transitions in single-phase materials , 2007 .

[15]  M. Meyers,et al.  Mechanical properties of nanocrystalline materials , 2006 .

[16]  H. Schadler.  Mobility of edge dislocations on {110} planes in tungsten single crystals☆ , 1964 .

[17]  K. Kurzydłowski,et al.  W/steel joint fabrication using the pulse plasma sintering (PPS) method , 2011 .

[18]  Huijun Li,et al.  Recent progress in research on tungsten materials for nuclear fusion applications in Europe , 2013 .

[19]  O. Kraft,et al.  Plasticity in Confined Dimensions , 2010 .

[20]  R. Pippan,et al.  Fracture Toughness Investigations of Severe Plastic Deformed Tungsten Alloys , 2006 .

[21]  M. Rieth,et al.  Optimization and limitations of known DEMO divertor concepts , 2012 .

[22]  J. Hohe,et al.  On the potential of tungsten–vanadium composites for high temperature application with wide-range thermal operation window , 2010 .

[23]  David E.J. Armstrong,et al.  Tungsten foil laminate for structural divertor applications – Analyses and characterisation of tungsten foil , 2012 .

[24]  R. Ruprecht,et al.  He-cooled divertor development for DEMO , 2007 .

[25]  E. Hall,et al.  The Deformation and Ageing of Mild Steel: III Discussion of Results , 1951 .

[26]  V. Vítek.  Core structure of screw dislocations in body-centred cubic metals: relation to symmetry and interatomic bonding , 2004 .

[27]  M. Lahaye,et al.  Brittle fracture of polycrystalline tungsten , 1985 .

[28]  D. Hull,et al.  Introduction to Dislocations , 1968 .

[29]  R. Pippan,et al.  Fracture toughness investigations of tungsten alloys and SPD tungsten alloys , 2007 .

[30]  D. Hull,et al.  Introduction to Dislocations , 1968 .

[31]  Masayoshi Kawai,et al.  Superplastic deformation in W–0.5 wt.% TiC with approximately 0.1 μm grain size , 2008 .

[32]  T. Mitchell,et al.  Work-hardening in niobium single crystals , 1963 .

[33]  Anton Möslang,et al.  Tungsten foil laminate for structural divertor applications - Tensile test properties of tungsten foil , 2013 .