基于气体捕捉法的泡沫Ti-6Al-4V等温发泡规律研究

Study on the law of isothermal foaming of Ti-6Al-4V foams fabricated by gas entrapment

为了确定气体捕捉法制备泡沫Ti-6Al-4V等温发泡过程中孔隙率和微观孔洞的变化规律,在不同发泡温度及发泡时间下制备了泡沫Ti-6Al-4V.运用阿基米德原理对泡沫Ti-6Al-4V的孔隙率进行测量,通过OM和SEM对其微观特征进行观察.研究表明:泡沫Ti-6Al-4V的孔隙率及孔径均随等温发泡温度升高而增加;但当发泡温度大于950℃时,孔隙率和孔径均减小,且孔洞形态由球形变成多边形,这是由于基体内生成大尺寸β相造成的.增加发泡时间能以促进孔洞长大的方式提高泡沫Ti-6Al-4V的孔隙率,球形孔洞数量随着发泡时间的增加逐渐增多.经950℃/10 h发泡得到了孔隙率34.2%、孔径平均值156μm、孔洞为球形且分布弥散的泡沫Ti-6Al-4V.

In order to determine the density of porosity and characterize the microstructure of pores in Ti-6Al-4V foams fabricated by gas entrapment method, different combination of isothermal foaming temperature and time of the process were studied. The density of porosity in Ti-6Al-4V foams was calculated through Archimedes method. The microscopic characteristics of the interior of Ti-6Al-4V foams were observed by using optical microscopy（ OM） and scanning electron microscopy（ SEM）. The results showed that the density of porosity and pore size increased with isothermal foaming temperature. But the porosity and pore size decreased and the pore morphology changed from spherical to a polygon shape,when the isothermal foaming temperature was above 950 ℃. This is believed to be attributed to the generation of large sized βphase. By adding isothermal foaming time,the population of porosity and spherical pores in Ti-6Al-4V foams can be increased in the same time. Ti-6Al-4V foams containing up to porosity of 34. 2% in the average pore size of 156 μm were successfully produced by gas entrapment at 950 ℃ isothermal foaming for 10 hours,while the pore morphology is sphere and pore is dispersed evenly.