Research On The Properties Of Mg-Li Alloy With Laminated Structure Processed By Accumulative Roll Bonding

With the properties of specific strength, specific stiffness, excellent anti-seismic and the resistance to the penetration of the particle with higher energy, Mg-Li alloys whose density is smaller than the Al-Li alloys that apply to aviation are the one of the most potential structural materials in future. In current, some parts of Mg-Li alloys have already been applied to smartphone, notebook and virtual reality devices. The electromagnetic radiation occurs during the devices above are working which will damage people health. Now, the research on the electromagnetic shielding of Mg-Li alloys has not been reported yet. And the Mg-Li alloys are limited its development because of the shortcoming of its lower strength. Consequently, the investigations that focus on the properties of electromagnetic shielding and mechanical of Mg-Li alloys are quite meaningful.In this article, the observation of metallography, microstructure and surface morphology by optical microscope and scanning electron microscope, properties measurement of conductivity, electromagnetic shielding and micro-hardness, the tensile test are to analyses the effects of roll-bonding and annealing on the Mg-Li alloys’properties of mechanical and electromagnetic shielding processed by accumulative roll bonding (ARB). The results are as following:(1) The alloy’s result of tensile test without roll-bonding shows that it has excellent ductility. The elongation of the tensile sample is 33%. The shielding effectiveness (SE) of the sample without roll-bonding are from 56-82dB at the range the 30-1500MHz.(2) With the increment of the rolling passes:the laminated structure of Mg-Li alloys are more visible. The tensile strength increase from 143.2MPa of unrolled sample to 248.8MPa of the fourth pass sample. The SE increased with the increment of the rolling passes too. The SE of the unrolled sample and fourth pass sample are 56-82dB and 72-84dB which can be attributed to the increment of the reflection and absorption loss.(3) The plasticity of the fourth pass roll-bonded sample after annealing increased, especially under the condition of 250℃+2h whose tensile strength is 216.7MPa and the elongation is 18.7% with the X gain size. From the aspect of the electromagnetic shielding, the SE increased because of the increment of conductivity caused by annealing, especially under the condition of 200℃+3h whose SE is 87-95db, which can be attributed to two aspects as follows:(a) the increment of the conductivity caused by annealing; (b) formulation of the grain boundary caused by annealing increase the attenuation of the reflection and absorption.