Fabrication and Characterization of Tungsten Heavy Alloys Using Chemical Reduction and Mechanical Alloying Methods

Abstract

A novel reduction technique has been developed to synthesize nano-sized tungsten heavy alloys powders and compared with the same powders processed by mechanical alloying technique. In the first method, nano-sized tungsten heavy alloys powders have been obtained by reduction of precursors obtained by spray drying of several appropriate aqueous solutions, which were made from salts containing tungsten, cobalt, and nickel. By adjusting the stoichiometry of the component of the solutions, it is possible to obtain the desired chemical composition of the tungsten heavy alloys powders. In the second method, highly pure elemental powders of tungsten heavy alloys have been mechanically alloyed in a tumbler ball mill for different milling time. The investigated tungsten heavy alloy powders with the composition (95%W-3.5%Ni-1.5%Fe), (93%W-4.5%Ni-1.0%Fe-1.5%Co), and (90%W-6%Ni-4%Cu) have been prepared using both methods. The prepared powders have been compacted at 70 bar (200 MPa) and sintered in vacuum furnace at 1400˚C. Vacuum sintering was carried out to achieve full densification of the produced tungsten heavy alloys. The investigated materials were going to be evaluated the physical and mechanical properties of the sintered parts such as density; electrical conductivity, hardness, and transverse rupture strength. The results reveal that, the grain size of alloys fabricated by chemical reduction technique (53.1-63.8 nm) is smaller than that fabricated by mechanical alloying technique (56.4-71.4 nm).

Effect of Transition Metals Oxides on the Physical and Mechanical Properties of Sintered Tungsten Heavy Alloys

“…The selected research work uses parameter levels in the same range of the applied one for the current investigation by the Taguchi method. Figure 11 shows the comparison of the measured properties of relative density, electrical conductivity, and hardness of this investigation with the other data [3,5,13] from previous research works. However, there are no valuable data for compression strength at room temperature of WHAs in literature.…”

“…For example, they provide sintered parts with high density, excellent mechanical properties and good corrosion resistance, and these properties are so attractive for different applications such as defense applications, radiation shielding manufacturing and civil applications. The microstructures in this type of composites typically consist of tungsten particles reinforced in a ductile matrix of a solid-solution alloy, such as Fe-Ni or Co-Ni [1][2][3][4][5]. Mechanical properties of tungsten heavy alloys are influenced by their microstructural features such as tungsten grain size, matrix volume fraction and W-W contiguity.…”

On the remarkable fracture toughness of 90 to 97W-NiFe alloys revealing powerful new ductile phase toughening mechanisms

“…Indeed DPT has been successfully applied in many brittle matrix systems [20][21][22][23]. Tungsten heavy (metal) alloys (WHAs), or composites, typically containing 78-98 wt.% W, along with a balance of ductile phase metals like Ni, Fe, Cu, Co, have been studied for several decades [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]. The WHAs are typically composed of W powders consolidated by liquid phase sintering (LPS).…”

The Effect of Mo and Dispersoids on Microstructure, Sintering Behavior, and Mechanical Properties of W-Mo-Ni-Fe-Co Heavy Tungsten Alloys

“…Furthermore, it has been reported that the addition of molybdenum to W-Ni-Fe alloys by mechanical alloying can enhance the hardness, yield strength, and ultimate tensile strength of the materials [13,14]. Additionally, the presence of cobalt in WHAs increases interfacial strength between the binder phase and tungsten matrix, which can improve both strength and ductility [15].…”