A New Ti/H phase transformation in the H2+ implanted titanium alloy studied by XRD, NRA, ERDA and SEM


A New Ti/H phase transformation in the H2+ implanted titanium alloy studied by XRD, NRA, ERDA and SEM

Wang, T.; Eichhorn, F.; Grambole, D.; Grötzschel, R.; Herrmann, F.; Kreissig, U.; Möller, W.

The titanium hydrogenation process in the H2+ implanted Ti225 titanium alloy has been studied in this work. The Ti/H phase transformation from hydrogen solid solution (hcp) to gamma phase titanium hydride (TiH(γ)) with a primitive tetragonal structure and then to a titanium-dihydride (TiH2(x)) with a body centred tetragonal (bct) structure has been characterized by X-ray diffraction, NRA and ERDA. This process is very different from the usual hydrogenation mechanism, in which the delta phase titanium-dihydride (TiH2(δ)) with a face centred cubic (fcc) structure is always involved. Both of the TiH(γ) and TiH2(x) are rare phase, which are formed under extreme conditions. The TiH(γ) was considered to be a metastable phase in low hydrogen concentrated titanium, and the TiH2(x) phase has not yet been notated. The characteristics of the TiH2(x) are unclear, but it is very stable at room temperature and exists as a mixture state with the titanium. A saturated fraction of the hydride to titanium phase has been obtained as about 15% (H/Ti~0.3) in a H2+ implanted sample.

Keywords: Titanium hydride; Hydrogen implantation; Phase transformation; X-ray diffraction; nuclear reaction analysis; elastic recoil detection analysis; scanning electron microscopy

  • Journal of Physics. Condensed Matter, 14(2002)1-10

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Publ.-Id: 4792