Development of re-crystallized W–1.1%TiC with enhanced room-temperature ductility and radiation performance

Abstract Ultra-fine grained (UFG) W–TiC compacts fabricated by powder metallurgical methods utilizing mechanical alloying (MA) are very promising for use in irradiation environments. However, the assurance of room-temperature ductility and enhancement in surface resistances to low-energy hydrogen irradiation are unsettled issues. As an approach to solution to these, microstructural modification by hot plastic working has been applied to UFG W–TiC processed by MA in a purified Ar or H2 atmosphere and hot isostatic pressing (HIP). Hot plastically worked compacts have been subjected to 3-point bend tests at room temperature and TEM microstructural examinations. It is found that the microstructural modification allows us to convert UFG W–1.1%TiC to compacts exhibiting a very high fracture strength and appreciable ductility at room temperature. The compacts of W–1.1%TiC/Ar (MA atmosphere: Ar) and W–1.1%TiC/H2 (MA atmosphere: H2) exhibit re-crystallized structures with approximately 0.5 and 1.5 μm in grain size, respectively. It is shown that the enhancement of fracture resistance by microstructural modifications is attributed to significant strengthening of weak grain boundaries in the re-crystallized state. As a result the modified compacts exhibit superior surface resistance to low-energy deuteron irradiation.

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

[2]  Y. Yamamoto,et al.  Deformability enhancement in ultra-fine grained, Ar-contained W compacts by TiC additions up to 1.1% , 2008 .

[3]  H. Kurishita,et al.  Current status of ultra-fine grained W–TiC development for use in irradiation environments , 2007 .

[4]  H. Kurishita,et al.  Observations of suppressed retention and blistering for tungsten exposed to deuterium–helium mixture plasmas , 2009 .

[5]  Hiroaki Kurishita,et al.  Development of ultra-fine grained W–TiC and their mechanical properties for fusion applications , 2007 .

[6]  Akira Hasegawa,et al.  Development of ultra-fine grained W–(0.25–0.8)wt%TiC and its superior resistance to neutron and 3 MeV He-ion irradiations , 2008 .

[7]  K. Tokunaga,et al.  Development of Tungsten Materials for Plasma Facing Components in Japan , 2007 .

[8]  A. Hasegawa,et al.  Improvement of Surface Exfoliation Behavior by Helium-ion Bombardment of a Tungsten Alloy Fabricated by Mechanical Alloying , 2009 .

[9]  J. Linke,et al.  Development of Nanostructured W and Mo Materials , 2008 .

[10]  H. Kurishita,et al.  Microstructure and Bend Ductility of W-0.3 mass%TiC Alloys Fabricated by Advanced Powder-Metallurgical Processing , 2005 .

[11]  Masanori Yamazaki,et al.  High temperature tensile properties and their application to toughness enhancement in ultra-fine grained W-(0-1.5)wt% TiC , 2009 .