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As a new type of neutron absorbing material, Al-Sm alloy has the advantages of low cost, high plasticity and high neutron absorption. After preparing the alloy into a foil, it can be used for neutron devices such as neutron collimator and Fermi chopper. The neutron transmittance of Al-Sm alloy was simulated by Monte Carlo simulation (MCNP), The results showed that when the Sm content increased above 20 wt.%, the neutron transmittance of the material in the range of 1-6 mm are less than 20%, Al-20Sm alloy satisfies the neutron absorption rate and has a certain plasticity. Al-20Sm alloy was prepared by vacuum induction melting, the microstructures and phases of the as-cast and heat-treated alloys were investigated by XRD, EDS and SEM. The results show that the as-cast microstructures are α-Al and β-Al4Sm. After heat treatment at 550 °C for 2 h, allotropic transformation occurs, and all β-Al4Sm in the alloy is transformed into γ-Al4Sm. After heat treatment at 550 °C for 300 h, and part of γ-Al4Sm undergoes crystalline transformation to form Al3Sm. The micromechanical properties of the Al-Sm intermediate compounds were tested by nanoindentation technique, in which the hardness of β-Al4Sm, γ-Al4Sm and Al3Sm were 8.97 GPa, 8.91 GPa and 9.89 GPa.