Effect of Ce on phase formation and magnetic properties of (Nd–Pr)_2.28Fe_13.58B_1.14 melt-spun ribbons

Abstract The phase formation of the (Nd_0.70Pr_0.30−xCe_x)_2.28Fe_13.58B_1.14 (x = 0.10, 0.15, and 0.20; hereafter defined as Pr₂₀Ce₁₀, Pr₁₅Ce₁₅ and Pr₁₀Ce₂₀, respectively) and (Nd_0.60Pr_0.40−yCe_y)_2.28Fe_13.58B_1.14 (y = 0.10, 0.20, and 0.30; hereafter defined as Pr₃₀Ce₁₀, Pr₂₀Ce₂₀ and Pr₁₀Ce₃₀, respectively) alloys that were prepared via the arc-melting method was investigated experimentally. The x-ray diffraction results revealed that all alloys annealed at 1173 K for 360 h consisted of a (NdPrCe)₂Fe₁₄B main phase with a tetragonal Nd₂Fe₁₄B-typed structure (space group P4₂/mnm) and an α-Fe minor phase, except for the Pr₁₀Ce₃₀ alloy, which contained an additional CeFe₂ phase. The magnetic properties of the (Nd_0.70Pr_0.30−xCe_x)_2.28Fe_13.58B_1.14 and (Nd_0.60Pr_0.40−yCe_y)_2.28Fe_13.58B_1.14 ribbons that were prepared by melt spinning were examined. The remanence (B_r) and maximum magnetic energy product ((BH)_max) of the (Nd_0.70Pr_0.30−xCe_x)_2.28Fe_13.58B_1.14 ribbons increased first and then decreased, whereas the coercivity (H_cj) of the ribbons increased with an increase in Ce content. The B_r and (BH)_max of the (Nd_0.60Pr_0.60−yCe_y)_2.28Fe_13.58B_1.14 ribbons increased, whereas the H_cj of the ribbons decreased gradually with an increase in Ce content. This changed behavior of magnetic properties is attributed to the variation of volume fraction of the α-Fe phase and different phase formations in the melt-spun ribbons. The Curie temperatures (T_c) of all ribbons decreased slightly with Ce substitution, which results from the lower Curie temperatures of Pr₂Fe₁₄B and Ce₂Fe₁₄B. The Pr₁₀Ce₃₀ ribbon with a higher Ce content exhibited optimal magnetic properties (B_r = 9.71 kGs, H_cj = 13.09 kOe, (BH)_max = 18.78 MGOe), which indicates that suitable magnetic properties of the Nd–Pr–Ce–Fe–B melt-spun ribbons can be achieved by alloy-composition and phase-formation design.