Formation of Intermetallic Compounds in Friction-Welded Joint of Aluminum Alloys to Copper and its Influence on Joint Efficiency

Abstract

Friction welding of aluminum alloys to copper was carried out in order to examine the weldability with particular reference to the effect of the intermetallic formation at the weld interface. The maximum joint efficiencies of A1050, 5000 and 6000 series alloys to copper were more than 80 %, while those of 2000 series and A7075 alloys joints were less than 50 % and scattered widely. For joints of A2024 and 5000 series alloys which contain rather high magnesium content, intermetallic compounds of Al-Cu-Mg system were formed at the weld interface in addition to that of Al-Cu system. In the other joints, only intermetallic compounds of Al-Cu system were formed. A mixing layer, in which pieces of copper and intermetallic compounds were incorporated into aluminum alloy, was formed near the weld interface. The mixing was very intense, in the joints with low efficiency, namely joints of A2011, A2024 and A7075 to copper, and these joints were fractured in this mixing layer and at the weld interface. On the other hand, the joints with high efficiency, namely joints of A5052 and A6061 to copper, had thin and even mixing layer. The mixing layers observed in the joints of A1050, A2017, A5056 and A6063 to copper were thinner than those of the other joints.

Ultrasonic Weldability of Al Ribbon to Cu Sheet and the Dissimilar Joint Formation Mode

“…For a sound rotary friction welded Al/Cu joint of 14 mm diameter produced under high pressure (40 MPa) for short time (1 s), Cu and IMC fragments were incorporated into weak Al piece adjacent to the interface by intense stripping and embroiling resulting from extremely high upset pressure (160 MPa), forming a mixing layer over a few tens of microns, and then no IMC layer was present at the Al/Cu interface. 24) For a sound linear friction welding of aluminum to copper of commercially pure grades (AA 1050 to C101) with a weld interface of 50 mm © 12 mm under the condition of 75 MPa friction/forge pressure, 50 Hz frequency, 2 mm oscillation amplitude and 2 mm burn-off distance, a large amount of copper particles and thin intermetallic (CuAl 2 phase) films around these Cu particles were incorporated into weak Al over 100 µm wide strip region, while the thickness of IMC layer at the weld line was calculated to be only 0.7 µm. 25) In linear friction welding of Cu/6063Al of 13 mm © 26 mm area to be welded, the Al and Cu remained contact but distinct, and Cu particles were entrained in the thermo-mechanically affected zone (TMAZ) on 6063Al side, especially for lower power input for relatively long friction time.…”

Joining phenomena and joint strength of friction welded joint between pure aluminium and low carbon steel

“…Generally speaking, forge pressure will be able to reduce the extent of a softened region from the joint and to improve the joint efficiency. 9,[31][32][33][34][35][36][37] In an attempt to push out a softened region on the P-Al side, the effect of forge pressure on joint efficiency was investigated. Figure 11 shows the relationship between the forge pressure and the joint efficiency of the joints.…”

“…This result differed from many results of friction welded joints between dissimilar materials. 9,[31][32][33][34][35][36][37] On the other hand, the tensile strength of the friction welded joints such as Al alloy/copper 36 and copper/steel 37 decreased with increasing forge pressure. That is, several friction welded joints made with higher forge pressure were fractured from the base metal although those joints did not achieve 100% joint efficiency.…”