High pressure structural study of quasicrystalline AlMn

High pressure X-ray diffraction studies have been performed on rapidly solidified AlMn alloys (35 and 40 wt.% manganese) containing the quasicrystalline phase. Pressure experiments were undertaken using a diamond anvil cell, and X-ray diffraction analysis in the energy dispersive mode was performed using the synchrotron radiation facility at HASYLAB-DESY in Hamburg. Both the quasicrystalline phase and the AlMn α phase were found to have stable structures for pressures up to 47 GPa and they showed reversible behaviour for decreasing pressures. Using a Murnaghan-type equation of state, the best values of the bulk modulus and its pressure derivative for the icosahedral phase were found to be B₀ = 146 GPa ∓ 10 GPa and B′₀ = 1.7 ∓ 0.5 respectively. The bulk modulus and the pressure derivative for the α phase are B₀ = 85 GPa ∓ 2GPa and B₀^′ = 2.9 ∓ 0.1 respectively.