Elsevier, Materials & Design, (89), p. 1181-1190
DOI: 10.1016/j.matdes.2015.10.083
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Spark plasma sintering was used to process Ni-W alloys from blends of Ni and W powders. The W amount ranged from 10 to 65 wt.%. XRD and EBSD investigations revealed the formation of Ni(W) solid solution along with clusters of pure W and remote quantities of WC or Ni6W6C carbide phases, depending on the initial W amount. The mechanical properties were investigated by tensile and hardness tests and compared to bulk Ni counterpart. Increasing the amount of W resulted in a grain size decrease of the Ni(W) component, probably due to grain boundary pinning by W solute atoms. This was also accompanied by an increase of both hardness and strength but at the expense of plastic strain. SEM investigations of the composite-like microstructures showed brittle fracture of the W clusters, whereas the Ni(W) solid solution counterpart exhibited a ductile behavior. Amongst the processed materials, the alloy containing an initial W amount of 30 wt.% exhibited the best combination of strength and uniform strain (800 MPa and 30%, respectively), which can be related to a cocktail-like effect coming from various strengthening sources, such as solid solution grain size reduction of the Ni(W), which also displayed a high number of Σ3 boundaries.