Diffusion bonding behavior and mechanism of 2 A12 aluminum alloy were investigated by diffusion bonding method in order to achieve the seamless construction of large section aluminum alloy. The interfacial healing experiments were carried out at 530

540

550 and 560 ℃

respectively

for 3 h and 5 MPa. The results indicate that with temperature increasing

large quantities of the second phase are dissolved and the micro zone suffers plastic deformation. The eutectic liquid phase breaks the oxide film and fills the micropores

where the internally decomposed oxide is dissolved into the matrix

and that at the edge is extruded by pressure. Grain boundary migration occurs in large quantities

and recrystallization regions appear on both sides of the interface. The dimension and distribution of recrystallized grains become more uniform with the increase of temperature

where the interface strength reaches the maximum of 318 MPa at 560 ℃.