Microstructure and Mechanical Properties of Al-20Sm Intermetallic Compounds

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 show that when the Sm content increased above 20%, 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, and 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 alpha-Al and beta-Al4Sm. After heat treatment at 550 degrees C for 2 h, allotropic transformation occurs, and all beta-Al4Sm in the alloy is transformed into gamma-Al4Sm. After heat treatment at 550 degrees C for 300 h, part of gamma-Al4Sm undergoes crystalline transformation to form Al3Sm. The micromechanical properties of the Al-Sm intermediate compounds were tested by nanoindentation technique. The hardness of beta-Al4Sm, gamma-Al4Sm and Al3Sm are 8.97, 8.91 and 9.89 GPa.