Hydrogen storage in high-entropy alloys with varying degree of local lattice strain

By M. Nygård, G. Ek, Dennis Karlsson, M. Sahlberg, M. Sørby, B. Hauback. International journal of hydrogen energy, 2019

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Abstract We have investigated the structure and hydrogen storage properties of a series of Ti, V, Zr, Nb and Ta based high-entropy alloys (HEAs) with varying degree of local lattice strain by means of synchrotron radiation powder X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry and manometric measurements in a Sieverts apparatus. The obtained alloys have body-centred cubic (bcc) crystal structures and form face-centred cubic (fcc) metal hydrides with hydrogen-to-metal ratios close to 2. No correlation between the hydrogen storage capacity and the local lattice strain δ r is observed in this work. Both bcc and fcc unit cells expand linearly with the zirconium-to-metal ratio [Zr]/[M], and increased concentration of Zr stabilizes the hydrides. When heated, the hydrides decompose into the original bcc alloys if [Zr]/[M]

Subfields: Aerospace Engineering, Materials Chemistry, Mechanical Engineering

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