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In this study, bulk Pr2Fe14B/ $\alpha $ -Fe nanocomposite magnets were fabricated from amorphous Pr9Fe86-x ${\text {Cu}}_{x}\text{B}$ 5 ($x$ = 0–1.5 at.%) precursors by a rapid high-pressure thermal compression (HPTC) technique, and the effects of Cu content on the texture and magnetic properties of the deformed magnets were investigated systematically. Results showed that the magnetic anisotropy $A_{m}$ and remanence $B_{r}$ of the deformed magnets increase evidently with increasing Cu content, whereas the coercivity $H_{\mathrm {ci}}$ decreases dramatically, thereby resulting in the maximum energy product (BH)max initial increase and then decrease. A magnetic anisotropy of $A_{m}$ = 0.44 and the optimal magnetic properties of (BH)max = 21.4 MGOe, $B_{r}$ = 13.1 kG, and $H_{\mathrm {ci}}$ = 3.52 kOe were achieved at x = 1.0 at.%, which can mainly be attributed to the strong ($00l$) crystallographic alignment of Pr2Fe14B nanocrystals and excellent exchange coupling between hard and soft nanocrystals. The present research is important for developing anisotropic bulk nanocomposites with high-energy products. [ABSTRACT FROM AUTHOR]

The poor fracture toughness of fine- and ultrafine-grained materials limits their structural applications. Here, nanoscale defect structures were introduced into fine grains ( d = 2–5 μm) of pure Zr by using cryorolling and subsequent annealing at 500 °C for 1 h. An ultrahigh fracture toughness, K IC = 146 MPa m 1/2 , was achieved in the sample, which was much higher than those, K IC = 79 MPa m 1/2 and 58 MPa m 1/2 , of coarse-grained and nanostructured Zr and reported values, K IC ≤ 103 MPa m 1/2 , of Zr and Zr alloys. The high fracture toughness was attributed to the suppressed propagation of cracks in the material due to the high strain hardening originated from the nanoscale defect structures within grains. The present work provides an alternative toughening strategy for fine- or ultrafine-grained materials. [ABSTRACT FROM AUTHOR]