Densification behavior of ultrafine W-Ni-Fe composite powders produced by a two-stage reduction process

The ultrafine composite powders of two different compositions (90W-7Ni-3Fe and 93W-4.9Ni-2.1Fe, wt%) were synthesized by a two-stage reduction process consisting of carbothermic pre-reduction and the following deep reduction by hydrogen, and then the densification behaviors of them were investigated. The prepared W-Ni-Fe composite powders by the new proposed two-stage method had the particle size ranged from 200 nm to 400 nm. The sintered compacts of these two kinds of W-Ni-Fe powders achieved nearly full densification at a sintering temperature of 1400 °C within 3 h. The maximum hardness of the alloys obtained at 1300 °C were 411 HV and 358 HV, and the bending strength of >1500 MPa was achieved at 1400 °C for the compositions of 90W-7Ni-3Fe and 93W-4.9Ni-2.1Fe, respectively. Meanwhile, the bending fracture mechanism was also investigated, which was different for the samples sintered at different temperatures.