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

Abstract

In this work, novel high-voltage electrical contacts of the W-Cu composites reinforced with tungsten fibers (Wf) have been fabricated by hot-press sintering and infiltration processes. Considering microstructural homogeneity and fabrication repeatability of the composites, Wf with the content of 3.3wt% was determined to be optimum for the reinforcement. By electroless deposition of ~2.5μm thick nickel layer onto the surface of Wf, the connectivity between the Wf 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 (Wp) during the Ni-activated sintering. Compared with the traditional commercial W-Cu composites, the W-Cu composite reinforced with the Ni-coated Wf 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.