15) Special Collection

15.a) Videos of brittle metals pulverized by the first H absorption

In this section 15.a, it is question of Hydride-forming intermetallic compounds.

Two examples of brittle metals are given : ZrMn1.5 and LaNi5.

As mentioned by D.P. Broom (1) "Most of the materials of practical interest  for storage applications decrepitate upon hydride phase formation, although some metallic hosts, such as Pd, do not.". This assertion perfectly illustrates that the formation of an Hydride does not necessarily means decrepitation (decrepitation = pulverization = the bulk host metal breaks up into fine powder). Note however that Pd (Palladium, Face-Centered Cubic) is a ductile metal and that the volumic mismatch between its Alpha phase (H-poor solid solution) and its Beta phase (H-rich solid solution) is about 9.8 % at RT, which is not that much.

That being said, most of the current Hydrogen storage compounds (being intermetallics) are brittle, so that decrepitation is difficult to avoid. But despite of its not-so-exciting connotations, the "decrepitation" aspect is actually of GREAT importance because it's a crucial part of the so-called "activation" process (of a given Hydrogen storage compound based on intermetallics). If you want to find out more about "activation" and "decrepitation", through the prism of intermetallics, we would advise you to consult e.g. :

- section 3.1.4 pp. 79-81 (+ the ref [60] page 80) in : D.P. Broom's book mentioned here above in this webpage in section 1.e.9 ;

- section 5.2.6 and 5.2.7 pp. 202-203 in : the book "H in intermetallic compounds II", 1992, mentioned here above in this webpage in section 1.e.2.

(1) in his 2011 book page 154. His book (Hydrogen storage materials, the characterization of their storage properties) can be found here above in section 1.e.9 in this webpage.

15.a.1) Video of ZrMn1.5 decrepitation

15.a.2) Video of LaNi5 decrepitation

Snapshots from the video. All the experimental details are precisely described in the movie (including the sound produced by the decrepitation !).

In addition to LaNi5, two alloys are presented : LaNi4.9Si0.1 and LaNi4.9Cu0.1.

Details about the video :

Title : Activation of a LaNi5 hydrogen absorbent.
Scientific collaborators : H.H. van Mal, H.A. van Esveld, H. Zijlstra.
Script : N. Wiedenhof, H. Zijlstra.
Photography, editing and direction : P.G.M. Vos.
Animation : W. Rouvoet.
Production :
      Photonics Department
      Philips Research Laboratories
      Eindhoven, Netherlands, 1973.

Acknowledgements (including to Philips) :

First of all, we sincerely acknowledge Philips for letting us the possibility to make their movie available on our website "for educational and non-commercial purposes only" (email dated : April, the 7th, 2021). We also warmly thank our Philips contact, Willem van de Leest, for his always-very-cordial-and-prompt emails.

Sincere and warm acknowledgements are also due to Daniel FRUCHART (Directeur de Recherche Emérite, Institut Néel, Grenoble, France) for having informed us about the existence of this super movie, back in 2016. Thank you so much !!

N.B. : while citing this video, please don't forget to mention the above details (see "Details about the video").
Of course, a little thank to the i2-HMR would also be appreciated ;)