Chemically produced tungsten–praseodymium oxide composite sintered by spark plasma sintering

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].…”

“…Regarding the aforementioned limitations, research is in progress to improve W and make it useful in future fusion reactors [4]. Currently, research in the field of plasma-facing materials focuses on determination of the impacts of ion irradiation on the properties of W [4]; improvements of its mechanical properties [1], such as its ductility [19] and fracture toughness [15]; methods to mitigate its brittleness [26]; and clarifications of the activation of this material [2].…”

“…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].…”

“…The wet chemical method, which differs from conventional solid-state synthesis approaches such as mechanical alloying, produces a combined powder using liquid phases. The wet chemical method produces the powder with relatively fine grains and no residual stress [26].…”