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/A1 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 μm in the case of extrusion speed of 0.3 mm/s to 2.78 μm in the case of extrusion speed of 2.1 mm/s.The thickness of interface transition layer increases significantly from 5.5 to 50 μm,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.