LAUSR

Abstract Evolution of microstructures and magnetic properties in bulk Nd-Fe-Cu-B based nanocomposites prepared by high pressure thermal deformation from amorphous precursors under different thermomechanical histories were investigated. We found that two-step isothermal deformation was favorable to the formation of (00l) texture of Nd2Fe14B phase and the enhancement of energy product compared with isothermal deformation, calefactive & isothermal deformation and isothermal & calefactive deformation, where a much higher energy product (BH)max = 22.8 MGOe was obtained for the former nanocomposite than those 15.6 MGOe, 17.3 MGOe and 20.1 MGOe for the latters, respectively. For the nanocomposites prepared by two-step isothermal deformation, the (00l) texture degree and the energy product increased with the first-step deformation-time up to 5 s then decreased, yielding the maximum magnetic anisotropy and energy product at 5 s. The magnetic anisotropy and energy product increased and then decreased with the temperatures increase from 500 °C to 560 °C in the first-step deformation, and the same change occurs in the second-step temperatures from 600 °C to 720 °C. The maximum anisotropy and energy product were obtained at 530 °C and 650 °C, respectively. The detailed mechanisms for these evolutions have been discussed.