Electron Beam Welding of Dissimilar Ti6Al4V and Al6082-T6 Alloys Using Magnetron-Sputtered Cu Interlayers

In the present work, the influence of a magnetron-sputtered copper interlayer on the process of electron beam welding of Ti6Al4V and Al6082-T6 plates was investigated. A sample without a filler was also prepared as a control. The microstructure, microhardness, and tensile properties of both samples were determined. Applying a copper interlayer resulted in the formation of an additional CuAl2 intermetallic compound in the form of a eutectic structure along the boundary of the aluminum crystal grains. A noticeable shift in the preferred crystallographic orientation of the aluminum phase from the denser {111} family of crystallographic planes in the case of the sample prepared without a filler towards less-dense ones such as {110}, {100}, and {311} in the case of applying a copper filler was observed. This was most probably caused by the lower free surface energy of the crystals oriented towards the {111} family of crystal planes, which favored the chemical bonding between the aluminum solid solution and the CuAl2 intermetallics. As a result of applying the copper interlayer, a noticeable increase in the microhardness of the weld seam was observed from 78 ± 2 HV0.05 to 136 ± 3 HV0.05. Applying a copper interlayer also led to an improved energy absorption capacity of the weld seam, as suggested by the increase in the UTS/YS ratio from 1.03 to 1.44. This could be explained by the smooth transition between the highly dissimilar Ti6Al4V and Al6082-T6 alloys. The UTS of the sample with the copper filler reached 208 MPa, which was about 60% of that of the base Al6082-T6 alloy.