Welding of aluminum alloys through thermite like reactions in Al-CuO-Ni system

摘要

In this work, first, a metastable composite powder of "14Al-3CuO-Ni" with a decreased ignition temperature was obtained via Arrested Reactive Milling (ARM), then this exothermic blend was used for welding of 1100 Aluminum alloy. The reactive media and the weld zones were investigated using scanning electron microscope. X-ray diffraction experiment and morphological investigations accompanied with the EDS analyses were carried out in order to evaluate the reactions' products. Vickers microhardness profile across the joint and the shear strength of the joints were determined. The weld zone thickness in each of the parent alloys was measured to be 750 μm, approximately. Results showed that different reactions occurring during the process lead to the in situ formation of different intermetallic compounds such as Al_3Ni_2 and Al_7Cu_4Ni as well as Al_2O_3 nanoparticles at the interface. Thus, this area has the maximum hardness (80-90 VHN) and the minimum hardness of 35 VHN belongs to the parent alloys. The mean shear strength of the obtained joints was 27 MPa.