Application of acoustic emission method to study metallic titanium hydrogenation process

https://doi.org/10.1016/j.ijhydene.2017.01.234Get rights and content

Highlights

  • The hydrogenation of titanium specimens is followed by acoustic emission signals.

  • The most intensive signals are generated due to specimens macro level cracking.

  • The ratio [H]/[Ti] corresponds to cracking depends on the specimen's specific surface.

Abstract

The changes occurring in metallic titanium specimens during hydrogenation, that are accompanying by high amplitude acoustic emission signals, have been studied. It was determined that the most probable reason for generation of these signals is crack formation in hydrogenated specimens as a result of internal stresses caused by structural changes in material. Also it was determined that typical sizes of the cracks are comparable with particle sizes of hydrogenated specimens, and the atomic ratio [H]/[Ti] in a solid phase, when crack formation is the most intensive, is generally lower for titanium sponge than for powder made from this sponge, which is explained by a larger specific surface of powder comparatively that of sponge.

Introduction

According to universally accepted definition [1] the acoustic emission is caused by short-time propagation of elastic waves generated as a result of quick energy release from sources localized inside some material. In particular, the acoustic emission phenomenon lies in generation of acoustic waves resulted from rearrangement of material internal structure [2]. This phenomenon is observed at various physicochemical transformations, in particular, at those accompanying interaction of metals or intermetallic compounds with hydrogen [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], that makes it possible to study these processes through recording and analyzing the acoustic emission signals. This paper is dedicated to the investigation of changes occurring in metallic titanium specimens at their interaction with hydrogen and followed by generation of high amplitude acoustic signals.

Section snippets

Materials and methods

In this work the subjects for investigation were specimens of metallic titanium in two various initial forms: titanium sponge with typical size of pieces ∼10 mm and titanium powder made of this sponge with particle size ∼40 μm and less. We investigated kinetics of interaction of these materials with hydrogen and recorded acoustic emission signals accompanying hydrogenation processes. A schematic circuit of the hydrogenation experimental setup is given in Fig. 1.

During the experiment the

Results

Fig. 2 provides typical time dependences of the atomic ratio value [H]/[Ti] in a solid phase during hydrogenation of titanium sponge and titanium powder.

It follows from Fig. 2 that hydrogenation reaction in both cases runs intensively at the very first seconds after hydrogen is supplied to a reaction chamber. As one would expect the rate of hydrogen absorption by titanium powder estimated by initial curve pieces of Fig. 2 is significantly higher than the rate of hydrogen absorption by titanium

Discussion

It is a well known fact that metal–hydrogen interaction is followed by changes in a crystal lattice of initial material due to formation, first, of solid solution (hydrogen in metal), and then, of hydride phases of various composition which, apparently, results in acoustical activity. Consequently, to explain the reasons for high-amplitude acoustic signals phenomenon, we have analyzed diagrams of titanium-hydrogen state obtained by various authors [18], [19], [20], [21], [22] and literature

Conclusion

Interaction between metallic titanium and hydrogen is followed by acoustic emission signals with a high amplitude generated on reaching some certain value of the atomic ratio [H]/[Ti] in a solid phase because of metal cracking at a macro level. The reason for cracking is in internal stresses initiated in a sample due to increasing volume of a solid phase as a result of changes in a material crystal lattice during hydrogenation. When the titanium powder is used, the atomic ratio [H]/[Ti] in a

Acknowledgements

The authors express their gratitude to M.V. Volonin and I.A. Tsareva for their assistance in performing experiments; to Yu.S. Ivanushkin and K.V. Korshunov for their assistance in analyzing experimental data and preparing manuscript; and to V.V. Popov and V.V. Tikhonov for their valuable comments during discussions.

This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.

References (23)

  • Inoue Hiroshi et al.

    Characterization of initial activation behavior for hydrogen storage alloys by acoustic emission technique

    J Alloys Compd

    (2007)
  • Cited by (4)

    • First principle calculations and low cost SLM processing of Ti–TiB composite materials

      2021, Materials Science and Engineering: A
      Citation Excerpt :

      Titanium alloys have good mechanical properties, excellent corrosion resistance and high biocompatibility, making them outstanding candidates for various applications in the chemical, biomedical, aerospace and automotive industries [1–5].

    • Assessment of subcritical crack growth in hydrogen-containing environment by the parameters of acoustic emission signals

      2018, International Journal of Hydrogen Energy
      Citation Excerpt :

      The process of crack propagation and fracture creates, as a rule, rather high amplitudes of AE signals [20] that can easily be recognized on the hindrances background. For example [21], where cracks initiation and propagation in hydrogenated titanium specimens using the method of AE has been investigated. As mentioned above, such cracks generated high amplitudes of acoustic signals.

    • Hydride-dehydride fine zirconium powders for pyrotechnics

      2021, International Journal of Energetic Materials and Chemical Propulsion
    View full text