Solution and segregation behaviors of impurity atoms in beryllium by experimental and theoretical investigations

Beryllium has been determined as one prospective neutron multiplier materials in nuclear fusion power plant. During the manufacturing of beryllium pebbles, impurities will be inevitably introduced into the beryllium matrix. However, the distribution of impurities in beryllium is lack of investigation. Consequently, in the present work, combined with experimental techniques and first-principles calculations, the solution and segregation behaviors of nonmetallic and metallic impurities in beryllium as well as the in-depth mechanism have been thoroughly investigated. The experimental observations have shown that the nonmetallic impurities of oxygen, carbon and silicon, the metallic impurities of iron, aluminium, magnesium, zinc, lead and copper could dissolve in bulk beryllium. The calculation results have shown that the solution energies of those impurity atoms is low except for that of lead. Furthermore, it has also been found experimentally that oxygen and iron could segregate at grain boundaries of beryllium. The segregation energy of oxygen and iron atoms at two grain boundaries of Σ 13 { 10 1 ̄ 1 } and Σ 11 { 10 1 ̄ 2 } are negative, which means that both oxygen and iron atoms have strong tendency to segregate at grain boundaries of beryllium. The results firmly demonstrate the observed phenomenon. The current work has contributed to a further understanding of the distribution of impurity atoms in beryllium, facilitating the manufacturing of beryllium pebbles.