Diffusion characteristics and mechanical properties of Mg–Sm system

The diffusion kinetics of Mg–Sm binary system in the temperature range of 723–798 K was systematically studied by solid–state diffusion technique. Four intermetallic compounds (IMCs) Mg 41 Sm 5, Mg 5 Sm, Mg 3 Sm and MgSm were observed in the diffusion zone. The diffusion coefficients and activation energies of the four IMCs were estimated based on the quantitative distribution of elements examined by the electron probe microanalyzer (EPMA). The Mg 5 Sm phase has the largest diffusion activation energy of 231.10 kJ/mol, while the Mg 41 Sm 5 has the smallest (111.45 kJ/mol). The mechanical properties of the four IMCs were investigated using nanoindentation technology and first-principles calculations. The nanoindentation tests show that the Mg 3 Sm phase possessed the largest Young's modulus (74.28 GPa) and hardness (3.01 GPa). The experimental results of Young's modulus and hardness of IMCs increase first and then decrease with the increase of Sm concentration, and the values calculated by first-principles calculations are close to the values of the experimental. The obtained diffusion kinetic properties and mechanical properties of the Mg–Sm system provide useful data for the development of new magnesium-rare earth alloys.