Hydrogen absorption and its influence on the thermal stability of Zr ₆₅Al ₁₀Ni ₁₀Cu ₁₅ amorphous alloy

The hydrogen absorption properties of Zr ₆₅Al ₁₀Ni ₁₀Cu ₁₅ amorphous alloy with a wide supercooled liquid region were evaluated using a Sieverts-type apparatus. The amorphous alloy absorbs 0.34, 0.80 and 0.85 wt.% hydrogen within 10, 6 and 5 min at 373, 473 and 523 K, respectively. According to Johnson-Mehl-Avrami-Kolmogorov (JMAK) theory, the hydrogen absorption activation energy of the amorphous alloy was 1.27 kJ mol ^-1. The pressure-composition (P-C) isotherms of the amorphous Zr ₆₅Al ₁₀Ni ₁₀Cu ₁₅ alloy at 573, 623 and 673 K did not show a plateau, and the hydrogen absorption capacities were 0.8, 1.3 and 1.7 wt.%, respectively. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analysis demonstrated that the thermal stability of the amorphous alloy was improved with an enlarged supercooled liquid region after the hydrogen uptake below 473 K, but was decreased after the hydrogenation above 523 K. The alloy still kept the amorphous structure after hydrogenation at 573 K, and transformed into the crystalline phases of ZrH ₂, ZrNi and AlCu after the hydrogenation at 673 K.