Development of tungsten-based materials by different sintering techniques

Tungsten-Based Composites for Nuclear Fusion Applications

“…W has unique characteristics, which have increased its value relative to other materials. The properties which confer this valuable status in nuclear engineering include its refractoriness, high melting point, high thermal conductivity, low thermal expansion coefficient, good chemical stability, high heat resistance, high sputtering threshold energy, low sputtering rate, low erosion rate at edge plasma temperatures of less than 40-50 eV, low deuterium/tritium retention rate, low tritium permeability, high moduli of elasticity, good thermal shock resistance, lack of hydride formation and adequate corrosion resistance [12,15,[18][19][20][21][22][23][24][25][26][27][28][29][30]. The use of W is associated with other advantages as well.…”

“…The behavior of W is undoubtedly advantageous for fusion applications, but the few drawbacks of W create areas for further research to make W more reliable. Inherently, W possesses a high ductile-tobrittle transition temperature (DBTT), low ductility and poor fracture toughness, low machinability and fabricability, low-temperature brittleness, radiation-induced brittleness, and a relatively low recrystallization temperature compared to its operation temperature [5,15,21,26,29]. The use of W above its recrystallization temperature interminably can be unsafe because its mechanical properties decrease in such an environment [19,21].…”

“…Inherently, W possesses a high ductile-tobrittle transition temperature (DBTT), low ductility and poor fracture toughness, low machinability and fabricability, low-temperature brittleness, radiation-induced brittleness, and a relatively low recrystallization temperature compared to its operation temperature [5,15,21,26,29]. The use of W above its recrystallization temperature interminably can be unsafe because its mechanical properties decrease in such an environment [19,21]. W is also associated with high embrittlement due to irradiation at low temperatures [4,22,24], and the DBTT of W increases with an increase in the radiation level [29].…”

“…Some of these techniques involve (i) W-based composites [19], (ii) nanocrystalline W-based materials [1,5,34], (iii) W-X (X=Ta, Re, Mo, V, Ti, etc.) alloys created by powder metallurgy [15,[35][36][37][38][39], (iv) the dispersion of ductile fibers in W by mechanical synthesis [25], (v) the dispersion of ceramic particles of transition metals [13], (vi) the addition of rare-earth oxide particles into W [26], (vii) effective energy dissipation caused by controlled cracking and friction at fiber/matrix interfaces [28], and the utilization of functionally graded materials (FGMs) as an efficient solution to the joining problem of W to copper-based heat sinks [34], (viii) the creation of laminated hybrid composites [18], (ix) the post-processing of W to obtain full densification [21], and (x) the addition of a sintering activator to obtain high density levels [21].…”

“…All of the abovementioned methods and techniques have some influence on the properties of W. For instance, equal-channel angular pressing (ECAP) reduces the brittleness and improves the toughness and strength of ultrafine (0.9 μm) equiaxed grains of W [21], as ECAP ultra-finegrained W exhibits much smaller cracks as compared to coarse-grained W around dents produced by microhardness tests even at 250°C [30]. Plasma spraying offers high adhesion and stability of thick W coatings on EUROFER steel [1].…”