HIGH-DENSITY Mo-W-Cu PSEUDOALLOYS BASED ON HOMOGENOUS Mо-25% W ALLOY POWDER 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 pseudoalloys (Mo–25% W)–20 vol.% Cu with a homogeneous refractory framework obtained by a single-time pressing and sintering of the dispersed mixture at temperatures 1400–1500 °C. The production of a dispersed granulated Mо–25% W alloy powder with a particle size of 0.1–0.3 mm through the decomposition of complex paratungstate and ammonium paramolybdate salts into oxide compounds xWO₃ · yMoO₃ with their subsequent recovery by hydrogen in a rotary chamber was studied. After recovery in hydrogen and depending on the temperature and decomposition time of complex salts in the moving layers, 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 powders Mo–25% W were compared with the corresponding properties of powders obtained in a stationary tube furnace in fixed layers. Temperature dependencies of porosity in pseudoalloys (Mo–25% W)–20 vol.% Cu 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 Mо–25% W alloy after sintering begin at the temperature 300 °C lower than when sintering mechanical mixtures of industrial metal powders. It has been shown that (Mо–25% W)–20 vol.% Сu pseudoalloys obtained by liquid-phase sintering at 1500 °C for 1 hour have the following characteristics: at 20 °C, the ultimate tensile strength σ_b = 490 MPa, relative elongation δ = 1.1, Brinell hardness НВ = 3.3 GPa, and at 500 °C — σ_b = 370 MPa, δ = 4.4, and НВ = 2.7 GPa.