High-Density Mo–W–Cu Pseudoalloys Based on Homogenous Mo–25% W Powder Alloy Produced by Reducing Oxide Powders in Moving Layers

Abstract

The article aimed to obtain a structural material with increased plasticity and density of 98.5–99.5% based on (Mo–25% W)–20 vol.% Cu pseudoalloys with a homogeneous refractory skeleton obtained by a single-time pressing and sintering of the dispersed mixture at temperatures 1400–1500°C. The production of a dispersed granulated Mo–25% W alloy with a powder particle size of 0.1–0.3 μm through the decomposition of complex ammonium paramolybdate and paratungstate salts into oxide compounds xWO3 · yMoO3 with their subsequent reduction by hydrogen in a rotary chamber was studied. Considering the temperature and decomposition time of complex salts in the moving layers, the physical and technological properties (such as phase composition, oxygen content, specific surface, bulk density, and tap density) of complex oxide powders xWO3 · yMoO3 and metal Mo– 25% W powders after reduction by hydrogen were compared with the corresponding properties of powders obtained in a stationary tube furnace in fixed layers. Temperature dependencies of porosity in (Mo–25% W)–20 vol.% Cu pseudoalloys after sintering at the temperature between 900 and 1500°C has been examined. It has been established that compaction of dispersed powder mixtures of (Mo–25% W)–20 vol.% Cu and homogenization of Mo–25% W alloy after sintering begin at the temperature 300°C lower than when sintering mechanical mixtures of commercial metal powders. It has been shown that (Mo–25% W)–20 vol.% Cu pseudoalloys obtained by liquid-phase sintering at 1500°C for 1 hour have the following characteristics: at 20°C, the ultimate tensile strength σt == 490 MPa, relative elongation δ = 1.1, Brinell hardness HB = 3.3 GPa, and at 500°C— σt == 370 MPa, δ = 4.4, and HB = 2.7 GPa.