Enhanced mechanical and arc erosion resistant properties by homogenously precipitated nanocrystalline fcc-Nb in the hierarchical W-Nb-Cu composite

To achieve a combined enhancement of mechanical properties with improved arc erosion resistance, a novel strategy of two-step ball-milling and hot-press sintering under hydrogen for fabricating hierarchical W-Nb-Cu composite reinforced with in-situ nanocrystalline fcc-Nb was advocated. Characteristics including phase constituents, microstructure, mechanical properties and arc erosion behavior of the W-3 wt.%Nb-30 wt.%Cu composite have been systematically investigated. The crystal structure, grain size and phase distributions, as well as the specified surface work function of the three components of W, Cu and Nb were identified by XRD, TEM, EBSD experiments and DFT calculation. The enhanced mechanical properties were considered to result from the grain refinement of W and Cu with gradient micron to ultrafine scale, and the interfacially precipitated nanocrystalline fcc-Nb, which also acted as the first breakdown phase for effective dissipation of arc energies.