Interstitial elements in Ti–13Nb–13Zr alloy produced by powder metallurgy using hydride powders

Abstract

Absorption of interstitial elements during the processing of Ti–13Nb–13Zr alloy using hydride powders was investigated. Oxygen, nitrogen and carbon contents were quantified in the steps of hydriding and milling of powders and after sintering of green compacts. The influence of the hydriding treatment was analysed regarding the interstitial contents in the raw materials. Milling and sintering were evaluated according to a 3³ factorial design considering the effects of milling time of titanium hydride from 1 to 11 h, sintering temperature between 1000 and 1400°C and holding time from 1 to 5 h. The results showed that the oxygen contents in sintered samples are strongly affected by the hydriding and milling of powders. The effects of the sintering temperature and holding time were found to be significant mainly for the increase in nitrogen and carbon contents. The results of the factorial design, along with the study of microstructural evolution allowed the optimisation of the process parameters in order to obtain the alloy with the lowest possible contents of interstitial elements and homogeneous microstructure.

Keywords:

• Titanium
• Ti–13Nb–13Zr
• Interstitial elements
• Powder metallurgy
• Factorial design

The authors wish to thank Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, proc.04/07664-2 and proc.08/04268-0) for the technician scientific and financial support.