| The liquid phase diffusion bonding of the 2090 Al-Li alloy has been investigated and effects of surface treatment, composition of insert metals and homogenizing heat treatment on the microstructure of bonded interlayer have been studied. Main results obtained in this study are as follows. 1) Good joint can be obtained by using Al-10% Si-1.5% Mg alloy as insert metal, but the eutectic structures in the grain boundary of base metal are observed. 2) When no cleaned base metals were bonded at 793K using Al-4.9% Zn as insert metal, oxide film(β-Al₂O₃and α-LiAlO₂) was seperated from base metal and subsequently moved toward the center of bonded interlayer. Properties of joint were poor. In joint of acid-cleaned base metal, properties of joint were improved. 3) Al concentration at the center of bonded interlayer was very high, because of dissolution phenomenon of base metal by liquid insert metal. 4) When acid-cleaned base metal was bonded for 3.6ks at 793K and homogenized for 86.4ks at 813K, the composition of bonded interlayer was similar to that of base metal, but the hardness of bonded interlayer was even lower than that of base metal. If homogenized joints were reheated for 1.8ks at 813K and then quenched, the hardness of bonded interlayer equivalent to base metal has been achieved and properties of joint were reasonable. |
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