Mechanical properties and electromagnetic shielding effectiveness of ZK60 magnesium alloy subjected to cold rolling and aging

Mechanical properties and electromagnetic interference (EMI) shielding effectiveness (SE) of extruded ZK60 alloy after pre-cold rolling and artificial aging treatment were investigated. Tensile testing was employed to evaluate the mechanical properties, and the EMI shielding property was measured by the coaxial cable method at ambient temperature. High densities of second phase precipitates and deformation twins were observed in the treated ZK60 alloys. Experimental results show that the specimens subjected to cold rolling and aging treatment possess remarkably improved mechanical strength and EMI SE compared with the extruded specimen. Artificial aging at 150 degrees C for 15 h after cold rolling is determined to be the optimum heat treatment condition, which results in a yield strength increase in 103 MPa and an SE enhancement of 15-20 dB in the testing frequency range 30-1500 MHz. The above mentioned observations are analysed in terms of abundant defects and MgZn2 phase precipitation in the ZK60 alloy.