Frictional Size Effect of Light-Weight Mg–Li Alloy in Micro Deep Drawing under Nano-Particle Lubrication Condition

In microscale due to the increase in the ratio of open to close lubrication pockets and escalation in coefficient of friction, unlike in macroscale, selection of proper lubrication condition has become challenging. In alignment with the aim of microforming, by the meaning of making light-weight energy effective micro-parts, in this study, the behaviour of a novel superlight magnesium-lithium (Mg-Li) alloy LZ91 is investigated during micro deep drawing under some lubrication conditions. Some heat treatments are undertaken to study the deformation behaviour of the Mg-Li alloy. To mitigate the effects of increasing in open to closed lubrication pocket ratio size effect, an innovative TiO2 oil-based nano-additive lubricant is applied, and its performance is determined in regard with the commonly used condition, dry condition. The mass fraction of nano-particles in the lubricant is a critical parameter which in this study 0.5 wt% and 1wt% are investigated. The results show the drawing force reduces significantly by utilising the 1wt% TiO2 oil-based nano-additive lubricant in comparison with 0.5 wt% of nano-particle lubricant and dry condition. The unique mechanism of the nano-particles is capable of retaining the lubricant inside surface asperities and hold it during the deformation process.