Metallurgy study of laser welded nickel and aluminum joint

Abstract

The metallurgy study of laser welded Nickel (Ni) and Aluminium (Al) lap joint configuration has been conducted. The seam weld was made by joining 0.20mm pure Nickel to 1.50mm pure Aluminium using QCW 900/9000 continuous laser mode with a recommended process parameter, which is done in stage 1, during the author’s internship with Molex. All materials were found weldable. To simulate actual product application, the weld joints were subjected to a comprehensive environmental testing per industry standard, IEC 60068. To understand the effect of the treatment tests on the welded joints, the specimens were then cross-sectioned to various views. Detailed visual inspection was performed using high magnification scope. No cracks and only 10% of voids were found for all cross-sectional views, with no significant difference in visual appearance for both treated samples and fresh samples. The intermetallic compound (IMC) formed due to the dissimilar material fusion welding were then analysed using Secondary Electron Microscopy Energy Dispersive X-Ray Analyzer (SEM-EDX). Vickers hardness test was done to investigate the correlationship between the intermetallic compound and its hardness. The homogeneity of the weld pools were predominantly formed by AlNi3and Al3Ni5 IMCs, depending on the melting and mixing of the Ni of the weld. Hardness tests further confirmed that the higher Nickel content of the weld pool would increase the hardness of the IMCs. However, in all cases, the treatment tests have no impact on the IMC content and hardness. The strength of the welds was also characterized using peel (pull) tensile test and analyzed using statistical tool. The strength of each individual groups were found different, however, it has no significant adverse effect on the strength of the welded joints.