Influence Of Hydrogen On The Thermal Stability Of Zr-Based Quasicrystals

Abstract

The high number of tetrahedrally coordinated sites for interstitial hydrogen and the favorable hydrogen-metal chemistry make quasicrystalline Zr-Cu-Ni-Al alloys a candidate for hydrogen storage applications. The icosahedral phase in Zr69.5Cu12Ni11Al7.5 has been shown to absorb electrochemically hydrogen up to H/M = 1.6. Only partially desorption of hydrogen was observed by TDA at about 500°C. Since hydrogen desorption seems to be hindered by a surface barrier, the hydrogen remains in the quasicrystal thus influencing their thermal stability. Such effects of hydrogen were studied by DSC and microstructural investigations. With increasing hydrogen content the decomposition of icosahedral Zr69.5. Cu12Ni11A17.5 is shifted to lower temperatures. Quasicrystals decompose by a discontinous transformation into the tetragonal Zr2Cu phase, the tetragonal Zr2Ni and the hexagonal Zr6NiAl2. Hydrogenation does not influence the phases formed during decomposition, but leds to the formation of a finer microstructure. We assume that the defects formed during the hydrogenation accelerate the nucleation of the stable crystalline phase.

High-pressure synchrotron radiation diffraction studies of icosahedral Ti-Zr-Ni and hydrogenated Ti-Zr-Ni quasicrystals

“…However, there is no clear difference between the B 0 -values for higher H/M content. This could be related to a recent study of hydrogenation of Zr-Cu-Ni-Al QCs [22], where, instead of the continuous increase of the specific volume per hydrogen atom, a decrease was observed at first as a function of the hydrogen content, up to H/M equal to 0.4. This was interpreted as indicating that the first hydrogen atoms expanded not only their interstitial sites, but also the neighbouring, still empty ones.…”

Heat Conduction to Photoresist on Top of Wafer during Post Exposure Bake Process: I. Numerical Approach

“…The best-studied examples are icosahedral (i) Ti-Zr/Hf-Ni [2][3][4][5][6] and Zr-Cu-Ni-Al [7][8][9][10][11][12][13][14]. The total loading capacity of QCs is competitive with the best known H-storage crystalline alloys (a hydrogen-to-metal ratio H/M ≈ 2.0 can be reached, whereas the maximum capacity per weight of 2.5% is less favourable), the absorption and desorption of hydrogen is quick and the alloys are made of low-cost materials.…”

Deuterium dynamics in the icosahedral and amorphous phases of the Ti40Zr40Ni20hydrogen-absorbing alloy studied by2H NMR

“…It has been demonstrated [1] that Ti-and Zr-based quasicrystals (QCs) exhibit favourable hydrogen-storage properties. The best-studied examples are icosahedral (i) Ti-Zr/Hf-Ni [2][3][4][5][6] and Zr-Cu-Ni-Al [7][8][9][10][11][12][13][14]. The total loading capacity of QCs is competitive with the best known H-storage crystalline alloys (a hydrogen-to-metal ratio H/M ≈ 2.0 can be reached, whereas the maximum capacity per weight of 2.5% is less favourable), the absorption and desorption of hydrogen is quick and the alloys are made of low-cost materials.…”