THERMAL STABILITY AND DEUTERIUM ABSORPTION AT ROOM TEMPERATURE OF Ti<SUB>36</SUB>Zr<SUB>40</SUB>Ni<SUB>20</SUB>Pd<SUB>4</SUB> QUASICRYSTAL

Ti-Zr-Ni quasicrystals can absorb a large amount of hydrogen, so have strong application potential in the hydrogen energy field and international thermonuclear experimental re- actor (ITER) program. However, the hydrogenation of the quasicrystals is often hindered and even poisoned due to their surface oxidation. To inhibit the oxidation, Pd has been selected, be- cause of its catalysis to hydrogen absorption, as a minor alloying element in Ti-Zr-Ni quasicrys- tals. In this paper, the Ti36Zr40Ni20Pd4 alloy was designed and its thermal stability and room- temperature deuteration were studied with XRD, DSC, OM, XPS and gas-solid reaction measure- ment apparatus. The XRD result shows that a single icosahedral quasicrystal (IQC) phase with a quasilattice constant aR=0.5174 nm was formed in the alloy by suction-casting method, which is metastable and transforms to conventional crystals tI-Zr2Ni and C14-TiZrNiPd (MgZn2 type) phase at about 400 . The deuteration test below the transformed temperature indicates that the al- loy can absorb deuterium up to a large concentration of 11.0 mmol/g (corresponding to 2.2%H, mass fraction) at room temperature after vacuuming and heating activation without any surface treatment. Once fully activated, the IQC can load deuterium rapidly with an absorption rate of 0.030 s �1 at ambient temperature, and has the quasilattice constant with about 5.5% expansion after two absorption cycles. The Ti36Zr40Ni20Pd4 IQC has better activation property and hydrogen capacity than the Ti40Zr40Ni20 IQC, which shows the catalyzing function of Pd.