Microstructure and mechanical properties of the ultra-fine grained ZK60 reinforced with low content of nano-diamond by powder metallurgy

ZK60 Mg alloys reinforced by Nano-diamond (ND) particles (0.05 wt%) were successfully fabricated by powder metallurgy followed with hot extrusion. ND particles and the precipitated MgZn2 phase were uniformly distributed in the matrix. Compared with the ZK60 Mg alloy, the tensile and compressive yield strengths of the composite exhibited an considerable improvements of ∼390 MPa and ∼430 MPa, an increase rate of ∼15% and ∼44%, respectively. The composite with 0.05 wt% ND exhibited an ultra-high strengthening efficiency, with tension yield strengthening and compressive yield strengthening efficiencies at 302 and 887, respectively. Furthermore, the composite showed an improved tension-compression yield symmetry. Based on theoretical analysis, the high strength of the composites is mainly attributed to thermal mismatch strengthening, grain refinement, Orowan strengthening and texture strengthening. •Ultrafine grained microstructure was obtained by powder metallurgy for the material.•Low content of particles result in a higher strengthening efficiency for composite.•The composite shows an obviously improved tension-compression yield symmetry.•The calculated values based on the model is close to the experimental strength.