In situ investigation on densification mechanism of Ti-20Al-19Nb (at.%) alloy by TiH2-assisted pressureless sintering

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dc.contributor.authorCai, Qi
dc.contributor.authorYu, Qilin
dc.contributor.authorLi, Xinyao
dc.contributor.authorLu, Yao
dc.contributor.authorLi, Yanmo
dc.contributor.authorCui, Ganggang
dc.date.accessioned2023-06-25T13:40:32Z
dc.date.available2023-06-25T13:40:32Z
dc.date.issued2023-06-20
dc.description.abstractDense Ti-20Al-19Nb (at.%) alloys can be cost-effectively fabricated by TiH2-assisted pressureless sintering; nevertheless, the densification mechanism remains controversial without understanding the entire sintering process. By in situ observing the surface morphology of the Ti/Al/Nb and Ti/TiH2/Al/Nb compacts upon heating, the densification mechanism of the Ti-20Al-19Nb alloys was elucidated in this study. In addition to the reported reason that the dehydrogenation of TiH2 provided reactive Ti, the densification of Ti-20Al-19Nb alloy was found to be strongly associated with the phase transformations upon sintering. The TiH2 participated in the reverse eutectoid transformation, α-Ti + δ-TiH2 → β-Ti, inducing the α/β and TiH2/β grain boundaries for the rapid diffusion of Al. The reaction of Ti(s) + Al(s) → TiAl3(s) was then accelerated, and the majority of the Al phase was consumed in the solid state, which significantly reduced the pores from the transient liquid Al. The activation energy of the Ti-Al reaction decreased with the addition of TiH2, and the growth mode of the TiAl3 phase was changed. By removing the large pores at 700 °C, the Ti-Al intermetallic phases were well connected, forming the continuous interdiffusion route for Ti, Al, and Nb. The diffusion of Nb, as well as the phase transformation of α2 → B2, was then promoted, and the ripening time for the B2 phase was increased. As a result, the density and mechanical properties were improved. The initial results of this study provided a foundation for the cost-effective fabrication of high-strength Ti-Al alloys containing refractory elements.en_UK
dc.identifier.citationCai Q, Yu Q, Li X, et al., (2023) In situ investigation on densification mechanism of Ti-20Al-19Nb (at.%) alloy by TiH2-assisted pressureless sintering. Journal of Materials Science and Technology, Volume 165, December 2023, pp. 170-186en_UK
dc.identifier.issn1005-0302
dc.identifier.urihttps://doi.org/10.1016/j.jmst.2023.04.068
dc.identifier.urihttps://dspace.lib.cranfield.ac.uk/handle/1826/19887
dc.language.isoenen_UK
dc.publisherElsevieren_UK
dc.rightsAttribution-NonCommercial-NoDerivatives 4.0 International*
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/*
dc.subjectTi-Al-Nb alloyen_UK
dc.subjectSintering mechanismen_UK
dc.subjectPorosityen_UK
dc.subjectIn situ observationen_UK
dc.subjectPhase transformationen_UK
dc.titleIn situ investigation on densification mechanism of Ti-20Al-19Nb (at.%) alloy by TiH2-assisted pressureless sinteringen_UK
dc.typeArticleen_UK

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