Correlation between anomalous hydrogen absorption and bonding56 strength in the Zr(AlxFe1-x)2 system

The nuclear-resonant-photon-scattering technique was utilized to monitor the iron binding properties in the intermetallic Zr(AlxFe1-x)2 system. The Fe56 isotope scatters elastically 8.512-MeV γ rays emitted by a Cr(n,γ) source. An experimental comparison of the scattered intensity from the different compounds reflects the corresponding variation of the iron cohesion properties. The experimental results were quantified by evaluating the mean vibrational kinetic energies or effective temperatures, Te, of the resonant iron nuclei in the specific compounds considered. The Fe56 effective temperature at room temperature was found to be 350(10), 337(16), 309(15), and 358(17) K for x=0, 0.083, 0.2, and 0.5, respectively. The results indicate clearly a minimum of the Fe bonding strength in the Zr(AlxFe1-x)2 compounds at x=0.2. This minimum correlates nicely with the maximum hydrogen absorption in the above intermetallic system, which may be therefore considered to provide further support for the rule of reverse hydrogen absorption capacity. The conclusions of the present study are utilized to indicate ways for tailoring hydrogen absorption behavior in certain cases.