Quantitative Evaluation of Interstitial Elements in the Processing of Ti-6Al-4V Alloy by Powder Metallurgy

The use of hydride powders in titanium powder metallurgy (P/M) is a low cost alternative for the manufacture of titanium alloys. However, due to the high reactivity of these powders, parts produced using this technique may contain interstitial impurities such as oxygen, nitrogen and carbon. In this work a factorial design approach was used to evaluate the influence of some stages of P/M upon the levels of these elements in sintered samples of Ti-6Al-4V. Milling time of titanium hydride powders, sintering temperature and holding time were evaluated. The effect of milling time was detected as the most significant for the increase in oxygen levels. The contents of all elements were affected by the increase of sintering temperature from 1200 °C to 1400 °C. Holding time was shown to be significant only for the carbon absorption in the samples sintered at 1400 °C.