Method for preparing high-density ultrafine-grained rare earth oxide doped tungsten alloy

Abstract

The invention provides a method for preparing high-density ultrafine-grained rare earth oxide doped tungsten alloy, and belongs to the field of powder metallurgy. The preparation method comprises thefollowing steps: preparing an oxide composite powder precursor by using ammonium metatungstate, rare earth nitrate, fuel and ammonium nitrate as raw materials and adopting a low-temperature solution combustion synthesis method, and then reducing by using H2 to prepare nano rare earth oxide doped tungsten alloy powder; and preparing the high-density ultrafine-grained rare earth oxide doped tungstenalloy by adopting multi-step discharge plasma sintering. According to the method, a low-temperature solution combustion synthesis method adopted can achieve the mixing at a molecular level, thus thetungsten oxide and the rare earth oxide in the obtained precursor are uniformly mixed, and the reduction product is alloy powder without subsequent special treatment; the SPS is suitable for rapid sintering of refractory metals and materials difficult to sinter, and the high-density ultrafine-grained rare earth oxide doped tungsten alloy can be obtained by adopting multi-step SPS; the relative density can reach 96-99%, and the average grain size is less than or equal to 300nm. The method has the advantages of simple and easily obtained raw materials, simple equipment and quick process, and issuitable for large-scale production.

Description

technical field [0001] The invention belongs to the field of powder metallurgy, and relates to a method for preparing a high-density ultrafine-grain rare earth oxide-doped tungsten alloy. Background technique [0002] Tungsten (W) has a high melting point, high hardness, good high-temperature strength, thermal conductivity, electrical conductivity, and low thermal expansion coefficient. It is widely used in national defense, nuclear industry, and high-temperature fields. However, the sintering temperature of W is usually higher than 2000 °C, which makes its densification difficult and causes grain growth. Refinement of W powder particle size to nanometer size can effectively reduce the sintering temperature of W, but the nano W powder will grow rapidly during the sintering process, which will reduce the mechanical properties of W alloy. Adding rare earth oxides (La 2 o 3 , Y 2 o 3 、Lu 2 o 3 、Ce 2 o 3 etc.) particles can prevent the movement of grain boundaries durin...

AI Technical Summary

Problems solved by technology

[0004] W is a difficult-to-sinter material. Using traditional sintering methods, it is difficult to obtain high density, and it needs to be sintered at high temperature for a long time, which will inevitably lead to grain growth, which is not conducive to the preparation of high-density ultra-fine grain W-based alloys.