Study On Preparation Of Ultra-fine Grain W-Ti Alloy

The rapid development of electronic information industry promotes the application of membrane technology,and W-Ti alloy membrane are widely used in junction of semiconductor devices as diffusion barrier because of its stable thermal-mechanical properties,low electron mobility and so on.At present,the industry W-Ti alloy contains lots of coarse grains and a large of titanium-rich phase that affects membrane's performances.In this paper,we used ultra-fine grain alloy powder to prepare W-10 wt% alloy by means of a hot pressing sintering technology.The preparation of ultra-fine grain alloy powder and the influence of sintering parameters on microstructure,morphology and performance of the alloy was studied,respectively.WO3 was prepared by a sol-gel method,the crystallization and the size of WO3 grain increased with the increase of temperatures and time.The optimal process was heat at 600? for 3h,the average size of WO3 was about 40 nm and the grain sizes distribution were homogeneous.The WO3 powder was reduced into W powder by hydrogen at tube furnace,the average size of tungsten powder was 80 nm.The W powder with the average grain size of 80 nm and TiH2 powder with the average size of 40 were ball-milled.After 10 h ball-milling,the TiH2 particles has a size of 300 nanometers and the particle size of W powder was not obviously changed.The W powder with the average grain size of 5?m and Ti powder with the average size of 100?m were ball-milled as comparison.After 24 h ball-milled,Pre-alloyed powders was composed of spherical particle,and dispersed particle was lamellar structures and had a size of about 200 nanometers.W-Ti alloy was prepared with W-TiH2 ultra-fine grain alloy powder and W-Ti ultra-fine grain alloy powder by hot-pressing process,respectively.The parameters of sintering process is 1300?,120 min and 120 MPa.W-Ti alloy prepared with two kinds of powder has similar solid solubility,density,grain size and hardness.W-Ti alloy prepared with W-Ti ultra-fine grain alloy powder contained lots of iron-titanium compounds.W-Ti alloy was prepared with W-TiH2 ultra-fine grain alloy powder by controlling the parameters of hot pressing sintering process.The results show that the sintering temperature,pressure and time have a significant effect on the material performance.When the sintering pressure was 100 MPa and sintering time was 120 min,the globular grains of W-Ti alloy was transformed into polyhedral grain with the increase of sintering temperature.W-Ti alloy prepared at 1200? was composed of rich-tungsten and titanium-rich phase,W-Ti alloy prepared at 1300? and 1400? was composed of rich-tungsten,titanium-rich phase and ?-Ti(W).The titanium in the alloy became more evenly with the increase of the sintering pressure and the extension of heat preservation time.Meanwhile,the solid solubility,density,grain size and hardness became larger.When the sintering parameter was 1400?,180 MPa,300min,the average grain size of W-Ti alloy was about 700 nm,density of alloy was above 98%.