Investigation of microstructure and tensile strength of TLP in the joint of AA2024-T4 alloys to AA6061-T6 using Sn-2.4Bi interlayer

AA2024-T4 and AA6061-T6 alloys were joined by diffusion bonding. 50μm tick Sn-2.4Bi foil was used as interlayer. Specimens with dimension of 130×32×3mm for strength test and 16×25×3mm for metallography were prepared by cutting. The bonding surfaces alloys prepared with 80 grit SiC finish. Alloys and interlayers were cleaned in ultrasonic bath of acetone for 10 min. Diffusion bonding was conducted in an atmosphere control tube furnace with heating rate of 5oC/min under argon gas at 2 atmospheres andat 253oC for 150,180, and 210 minutes for 50μm tick Sn-2.4Bi interlayer. Tensile strength of the joint after 210 min for 50μm tick Sn-2.4Bi interlayer was 12.3MPa. Jointswere observed and examined using SEM and mapping Element. Bi is distributed homogeneously in two base metal. Cu and Mg elements penetrated more than Al in theinterlayer.