Homogeneous nanocrystalline Ni–Co alloys with excellent mechanical properties via abrasive-assisted electroforming

The current major challenge is to impart homogeneous nanocrystalline Ni–Co alloys simultaneously with high strength and sufficient ductility as well as low internal stress to achieve a desirable strength–ductility and internal stress combination. We successfully produced homogeneous nanocrystalline Ni–Co alloys exhibiting ultrahigh strength, appreciable ductility and low internal stress, using abrasive-assisted electroforming (AAEF) with free ceramic beads. Distinctively, the AAEF process exerts uniform shear by the friction of ceramic beads rather than the conventional direct current electroforming, which makes it feasible to synthesize homogeneous nanocrystalline Ni–Co alloys with outstanding mechanical properties. Our results demonstrated that the structure of the Ni–Co alloys (AAEF) consists of equiaxed nanocrystals with an average grain size in the range of 43.0–54.7 nm. Surprisingly, the homogeneous nanocrystalline Ni–Co alloys (AAEF) exhibited excellent microhardness, yield strength, tensile strength, fracture elongation and low internal stress. Consequently, AAEF is a promising method for synthesizing homogeneous nanocrystalline Ni–Co alloys simultaneously with ultrahigh strength and respectable ductility as well as low internal stress. This work provides a novel practical strategy for designing and fabricating homogeneous nanocrystalline materials with desirable mechanical properties for applications in metallic molds and X-ray telescopes.