WRC 385

The joining of 6061 aluminum reinforced with 15 volume percent Al?O? was studied. Transient liquid phase bonding with silver, copper, and aluminum-12 atomic percent silicon were the three systems which demonstrated an ability to join the aluminum based composite. The physical phenomena controlling transient liquid phase bonding of aluminum alloys were also examined to gain a better understanding of the joining process. Each joint was made in a vacuum furnace using a spring or screw loaded fixture to provide 30 kPa (5 psi) of pressure on the faying surfaces. The bonding was performed at temperatures ranging from 10°C above the solidus of the composite (582°C) up to the eutectic temperature of the Al-(Ag, Cu, or Si) systems. The study of each joint included a shear test, metallographic and compositional examination of the joint, and tensile tests of the strongest braze systems. Joining with both the silver and the Al-12Si showed consistently good results, while the copper was less consistent, but provides the largest joining temperature range. Though Al-Ag and Al-Cu eutectic alloys were not used because they were not available in a suitable thin sheet form, these alloys could produce reliable joints at lower brazing temperatures.