Ultrafine Tungsten Rhenium Alloy Single Phase α-study On The Preparation Principle And Technology Of Solid Solution Powder

Tungsten-rhenium alloys have a series of excellent properties,such as high strength,high hardness,high-temperature corrosion resistance,good toughness,and radiation resistance.They have been widely used in high-temperature measurement,electrical vacuum technology,electrical contact materials,spraying materials,nuclear fusion,and aerospace fields.The preparation of excellent ultrafine tungsten rhenium alloy powder is the foundation and key to the production of high-performance tungsten rhenium alloys.There are few studies on the preparation of ultra-fine tungsten-rhenium alloy powder in China.In this paper,three methods for the preparation of ultra-fine tungsten rhenium alloy powder have been used,and the preparation of ultra-fine tungsten rhenium alloy powder has been studied in coordination with hydrogen reduction.Furthermore,an ultra-fine tungsten-rhenium alloy single-phase solid solution powder has been prepared.The specific research contents are as follows:1.Firstly,tungsten-rhenium alloy powder was prepared by evaporative crystallization in collaboration with hydrogen reduction.During the process of preparing precursor by evaporative crystallization,it was found that adding glucose could inhibit the adverse effect of"volatilization deposition"caused by water vapor generated during the precursor reduction process.Using this method,tungsten-rhenium alloy powder with an average particle size of 115.35 nm was prepared.During the process of preparing the precursor by evaporative crystallization,it was found that adjusting the p H of the solution to≤1 can refine the precursor powder.Due to the genetic effect of particle morphology,an ultrafine tungsten-rhenium alloy single-phase solid solution powder with an average particle diameter of 105.39 nm and a uniform composition distribution was finally prepared.2.In order to prepare ultrafine tungsten-rhenium alloy powders below 100 nm,a method of high-energy ball milling combined with carbon-assisted hydrogen reduction was introduced in this paper.During the research,the effect of adding glucose during high-energy ball milling on the particle size of the prepared powder was investigated,and it was found that adding glucose can refine the powder.The influence of carbon ratios of 0.2,0.4,0.6,0.8,and 1.0 on powder particle size was also investigated.It was found that the best effect was obtained when the carbon ratio was 0.8.The effect of different depths of hydrogen reduction on the particle size of the powder was investigated.It was found that too high a temperature would cause severe intergranular aggregation and growth.Finally,a single-phase tungsten-rhenium alloy solid solution powder with an average particle size of 48.66 nm and a uniform composition distribution was prepared by deep hydrogen reduction at 830°C.3."The hydrothermal method can avoid the disadvantages of mechanical alloying and reduce the introduction of impurities.It has been found that adding oxides such as the second phase La₂O₃,Y₂O₃,and Th O₂ during the hydrothermal process can significantly reduce the grain size of tungsten alloys prepared by subsequent sintering,reduce grain boundary stress,improve low-temperature brittleness and recrystallization temperature,and play a dispersion strengthening role.Therefore,in the end of this paper,the preparation of ultrafine tungsten rhenium alloy powder by hydrothermal method combined with hydrogen reduction was studied,A hydrothermal method was designed to prepare nano-tungstate aggregates that are insoluble in water under both acidic（p H=0.2）and alkaline（p H=10）conditions.Finally,nano-spherical and flaky tungsten rhenium alloy powders were prepared using a coordinated hydrogen reduction method,respectively.Because PVP is often used to refine grains in hydrothermal synthesis,subsequent studies on PVP nano dispersants have found that adding PVP during the hydrothermal process can refine the grains.Due to the genetic effect of the morphology of precursor particles,ultrafine tungsten-rhenium alloy single-phase solid solution powders with an average particle size of 81.51 nm and a uniform composition distribution have been prepared under acidic conditions.