Roll bonding mechanism for Mg/Al composite plate based on electron work function in the initial stage

Mg/Al laminate composites were prepared at 400 celcius for 15 min through single-pass rolling with reduction ratio from 10 to 27%. The bonding mechanism of the initial bonding stage under low pressure was studied. Two critical statuses (beginning bonding and complete bonding) are found at the reduction ratio of 14.5% and 21.75%. In this article, the coincidence of the ratio of external force (normal stress) and internal force (electronic force) at the two critical points shows that electrons overcome the potential barriers of Mg and Al respectively and make them move freely to form metal bonds. The free movement of electrons between two metal interfaces forms a metallic bond, which bonds the two metals. The formation of metallic bonds overcomes the classical barrier to achieve electron free motion. The ratio of sigma(Mg) to sigma(Al) (sigma(Mg)/sigma(Al)) is 0.7340, and the ratio of f(Mg) to f(Al) (f(Mg)/f(Al)) is 0.7988, where it can be found that the former agrees well with the latter. The good agreement between theory and experiment proves that overcoming the potential barrier plays an important role in the early bonding stage of bimetal composite plates.