Effect of B and C doping on structure and magnetostriction of high-Pr content alloys

► High-Pr content alloys containing B and C are prepared with MgCu 2-type structure. ► B and C atoms occupied interstitial or substitutional sites in the alloys. ► Lattice parameter increases at first with increasing B content and then decreases. ► Magnetostriction of the high-Pr content alloys is improved by B and C doping. ► High-Pr content alloys containing B and C are promising magnetostrictive materials. The structure and magnetostriction of the high-Pr content (Tb 0.2Pr 0.8) (Fe 0.4Co 0.6) 1.88− x C 0.05B x (0 ≤ x ≤ 0.08) alloys homogenized at 700 °C for 7 days have been investigated by X-ray diffraction and magnetic measurement. It was found that the matrix of the (Tb 0.2Pr 0.8) (Fe 0.4Co 0.6) 1.88− x C 0.05B x alloys belongs to (Tb, Pr) (Fe, Co, C, B) 2 phase with MgCu 2-type structure. The Curie temperatures are derived from M–T curves, which showed a slight increase when 0 ≤ x ≤ 0.06, then decreases with further increasing x. The composition dependence of magnetostriction λ a (= λ ∥ − λ ⊥) for (Tb 0.2Pr 0.8) (Fe 0.4Co 0.6) 1.88− x C 0.05B x alloys reaches a maximum value at x = 0.01 at room temperature. The double split (4 4 0) lines of the Laves phase overlap gradually with increasing x and finally approach to form a broadened peak for x = 0.03. The spontaneous magnetostriction λ 111 decreases with increasing boron contents.