Dynamic mechanical analysis of copper-containing magnetic Pr–Fe–B alloys

Abstract The mechanical properties of magnetic alloys with compositions Pr 17 Fe 76.5 B 5 Cu 1.5 and Pr 17 Fe 73.5 B 8 Cu 1.5 were studied with the aid of a dynamic mechanical analyzer. The elastic modulus of the annealed Pr 17 Fe 76.5 B 5 Cu 1.5 alloy varied substantially (∼24%) and irreversibly when it was heated to 450 °C and cooled to room temperature. Conversely, the elastic modulus of the annealed Pr 17 Fe 73.5 B 8 Cu 1.5 alloy varied only slightly upon heating to 450 °C and cooling to room temperature. This behavior has been attributed to the precipitation of excess rare earth from the lattice of the matrix phase and to the Pr 6 Fe 13 Cu and Pr 1+e Fe 4 B 4 phases.