Rare Earth Y-doped Rare Earth Element Y In The W-ni-fe Composite Powder And Alloy Preparation Study On Occurrence Of,

High-density tungsten-based alloys with a series of excellent physical, mechanical properties, plays an irreplaceable role in the field of military and civilian. Refinement of tungsten grain organizations can increase high-density tungsten alloy performance, fine-grained material tungsten alloy has become one of the hot study spots in today's world. The core of preparation high-performance fine-grained material tungsten-based alloys is preparation Nano / ultra-fine powder and control alloy grain growth. Add trace elements of ultra-fine powder, refined alloys has become an important research direction,this paper conducts a more systematic, more specially studies about the preparation of nano-W-Ni-Fe composite powder and alloy against add Y , which is further modified in-depth study of rare earth high-density tungsten-based alloys provide a theoretical and experimental basis.The method of Spray-dried is used to prepare W-Ni-Fe precursor powder with add different content Y in this experimental. Reducing the precursor powder by a two-step reduction process. the composite powder phase composition and changes in law with adding rare earth Y is studied . The results show, the rare earth Y and W formed by complex oxides phase Y₂W₃O₁₂ after calcined at 600℃. The complex oxides are very stable during hydrogen reduction of less than 600℃. When the temperature reaches 700℃, some tungsten in complex oxides phase is reduced, the rare earth phase is Y₂WO₆ with adding Y content of 5% , the rare earth phase is Y₂WO₆ and Y₆W₂O₁₅with adding Y content of 10% and 20%. Air phase transfer which mainly resulted in growth of particles during reduction was put forward. With the increasing of vapour produced during reduction, volatile WO_X·nH₂O was easy synthesized by tungsten oxide and vapour WO_X·nH₂O deposited in surface of oxide tungsten with lower chemistry value or metal tungsten powder and resulted in growth of particles. Adding rare earth Y were put forward in order to inhibit growth of particles in this paper. When adding rare earth elements Y, Complex oxides phase formed and adsorbed on surface of metal tungsten particles or tungsten oxide particles. The rate of producing volatile WO_X·nH₂O was prevented from synthesizing of tungsten oxide and vapour, then air phase transfer was decreased. Growth of powder particles were hold back. When the rare earth element content changes from 0 wt% to 20 wt%, with the increasing of the rare earth elements content, the Particle sizeof the composite powder improved distinctly.In-depth study the distribution and morphology of the rare earth element Y in the alloy ,and explain the relationship between the rare earth element Y and the properties and microstructure of alloy. Rare earth element Y formed by Y₂O₃ in the alloy, With the increase of the rare earth element Y, the grain of tungsten decreased. Add rare earth element Y 0.4wt%, the liquid phase sintering temperature lower, a small amount of rare earth Y can increase the grain size of tungsten transgranular cleavage fracture and improve the ductility alloy, and has played an effective grain refinement. With rare earth Y increasing, the Y-rich region in the alloy appears, and rare earth Y-gradient from the tungsten particles from the point of tungsten particles to the brink of regional decline. Excessive content of rare earth ,the properties of alloy decreased.