Influence of nano-diamond content on the microstructure, mechanical and thermal properties of the ZK60 composites

The effect of nano diamond (ND) content on the microstructure, mechanical properties, and thermal conductivity of ZK60+x (x = 0, 0.05, 0.1, 0.15, 0.2 wt.%) ND composites were investigated. The microstructures of ND/ZK60 composites were observed, which indicated that the nanoscale MgZn2 and ND particles distributed evenly in the α-Mg matrix. The tensile yield strength (TYS) and compressive yield strength (CYS) of the composites first increased remarkably and then decreased with further increasing the ND content. Due to the surface area of the matrix-diamond interface increased and the grains sizes of composites decreased with the amount of ND increase, which cause the coefficient of thermal expansion (CTE) of the composites reduced significantly. Meanwhile, the thermal conductivity of the composite material decreases from 129 W·m − 1·K − 1 to 116 W·m − 1·K − 1 with the content of ND increasing from 0.05% to 2.0%. The thermal conductivity of the composites increases to the maximum and then decrease with the increase of temperature (in temperature range of 273 - 573 K). The ZK60+0.05 ND showed superior mechanical and thermal conductivity property, TYS of 343.97 MPa, CYS of 341.74 MPa, elongation of 15.71%, CTE of 7.3 × 10−6 K − 1, and thermal conductivity of 129 W·m − 1·K − 1 at room temperature. It is demonstrated that the ND content has an obvious influence on the microstructure, mechanical properties, and thermal conductivity of ND/ZK60 composites.