Fabrication and properties of the W-Cu composites reinforced with uncoated and nickel-coated tungsten fibers

In this work, novel high-voltage electrical contacts of the W-Cu composites reinforced with tungsten fibers (W-f) have been fabricated by hot-press sintering and infiltration processes. Considering microstructural homogeneity and fabrication repeatability of the composites, Wf with the content of 3.3 wt% was determined to be optimum for the reinforcement. By electroless deposition of similar to 2.5 pm thick nickel layer onto the surface of W-f, the connectivity between the W-f and its neighboring W-Cu matrix after sintering and infiltration was improved with the elimination of porosity. This was considered to be ascribed to the plastic deformation of Ni-coatings during the molding of green compacts and the improvement of rearrangement of tungsten particles (W-p) during the Ni-activated sintering. Compared with the traditional commercial W-Cu composites, the W-Cu composite reinforced with the Ni-coated W-f provided desirable increased tensile strength by 15.8% and improved electrical breakdown strength by 65.3% after the interface tuning, which is applicable and transferrable to other refractory metals for property improvement.