The effects of ball milling and the addition of blended elemental aluminium on the densification of TiH2 power

Abstract

International audiencePowder production and sintering processes of titanium powder metallurgy are studied in order to reduce the cost of manufacturing titanium parts. The direct sintering of TiH2 simplifies powder processing and helps densification during sintering. The effects of ball milling have been shown to improve the dehydrogenation of TiH2, which during sintering, causes the earlier dissolution of the oxide layer surrounding the solid titanium particles, allowing solid diffusion to occur earlier. The combined effect of reduced particle size and increased dehydrogenation of ball milled TiH2 are studied here during sintering, in order to understand their roles during densification. TiH2 ball milled for various durations is vacuum hot press sintered at 700–900 °C. The density, microstructure and hardness of the fabricated titanium specimens are also studied. The effects of ball milled powder on the introduction of blended elemental aluminium are studied in comparison with a commercial titanium powder. The increase in ball milling duration of TiH2 powders to reduce particle size causes faster densification and dehydrogenation, with a finer uniform microstructure. When using fine ball milled powder with aluminium, the formation of Kirkendall pores through the interaction of titanium and liquid aluminium is worsened

In Situ Ti6Al4V/TiB Composites Prepared by Hydrogen-Assisted Sintering of Blends Containing TiH2 and Ball-Milled Ti+TiB2 Powders

“…To achieve enhanced sintered densities (reduced porosities) of BEPM-produced titanium alloys, preliminary activation of raw powders or powder blends by milling can be successfully used [ 18 , 19 , 20 ]. The same treatment is a potential way to improve sintered microstructures of TiB reinforced composites.…”

Influence of processing parameters on dehydrogenation of TiH2 in the preparation of Ti–Nb: A review

“…The combination of powder metallurgy and mechanical alloying increases the homogeneity of alloy compositions by combining different elemental powders at the atomic level through rapid welding and fracturing with high-energy ball milling. Numerous studies have discussed the preparation of Ti-based alloys using a combination of the mechanical alloying and powder metallurgy routes, followed by the sintering process [ 20 , 21 , 22 ].…”