Influence of Extrusion Speed on the Microstructure Evolution, Interface Bonding and Mechanical Response of Mg MB26/Al 7075 Composite Rod

Abstract

The Mg MB26/Al 7075 composite rod, in which Mg MB26 serves as the sleeve and Al 7075 serves as the core, is fabricated via the process of co-extrusion. The influence of extrusion speed on the microstructure evolution, interface bonding and mechanical response of the Mg MB26/Al 7075 composite rod is investigated. The results show that the typical extrusion texture of Mg sleeve does not change during co-extrusion; however, the average grain size in the Mg sleeve slightly changes from 1.57 lm in the case of extrusion speed of 0.3 mm/s to 2.78 lm in the case of extrusion speed of 2.1 mm/s. The thickness of interface transition layer increases significantly from 5.5 to 50 lm, and therefore, the interface bonding becomes deteriorative with increasing extrusion speed; in particular, many cavities emerge in the case of 1.2 and 2.1 mm/s.