Welding of Al Alloys Through In Situ Fabrication of Al₃Ni Intermetallic Compound Using Combustion Synthesis

Abstract

The exothermic reactions in Al+Ni system were used as a power source for welding of Al1100 alloy so that the obtained joint was reinforced with in situ produced Al 3 Ni intermetallic compound, simultaneously. Due to the combustion heat, the surfaces of the plates were melted down which, in turn, eventuated in formation of a strong surficial bond. The cross sections of joints were analyzed using optical microscopy, EDS-equipped scanning electron microscopy (SEM), and X-ray diffraction experiments. XRD and EDS results represented the Al 3 Ni intermetallic compound as the reaction product. The compressive shear strength of the joint was 20 MPa. INTRODUCTIONAluminum welding is more challenging rather than welding of other metals and alloys due to its high thermal conductivity and high oxidation rate characteristics. The problem would be overcome if the power source can release a large amount of energy (in the form of heat) in a short time. Combustion synthesis or self-propagating high temperature synthesis (SHS) reactions provides such a necessity. In our previous work. [1] Al alloys were joined using the exothermic reactions in Al-CuO-Ni system in which a pre-stage of mechanical activation was required in order to decrease the ignition temperature of the utilized powder mixture. In this work, Al+Ni powder mixture was used for welding because its ignition temperature is lower than melting point of Al, thus the pre-stage of mechanical activation is not necessary, which in turn makes the process more economical.

Elaboration of the Al-Al3Ni Alloy Eutectic by a Carbothermal Process

“…A large variety of methods were reported for the aluminum alloys Al-Al 3 Ni involving casting [6,[12][13][14][15][16][17][18][19][20][21][22][23][24][25], solidi cation [26][27][28][29], arc melting [28], combustion method [27], aluminothermic reduction [30], mechanical alloying [31], and high-pressure torsion (HPT) [32]. Each of these methods has its advantages depending on the eld of application.…”