Homogenizing interfacial IMC distribution and enhancing strength of laser welded-brazed Al/Ti butt joint by oscillated scanning

Al/Ti dissimilar metals were fabricated using laser weld-brazing technology under three different scanning paths (straight, infinite, and circular). When scanning path changed from straight to infinite and circular, interfacial IMC thickness would be smaller and smaller. Thinnest IMC of 1.1–3.0 μm would be produced under circular scanning path. Analysis of the interfacial IMC composition confirmed the formation of Ti(Al,Si) 3 under all three scanning paths. Interfacial thermal cycles calculated results indicated that a circular scanning path would result in the lowest peak temperatures, resulting in the thinnest IMC layer. Lowest tensile strength of 177.9 MP would be obtained under straight paths. When a straight scanning path was adopted, fracture occurred at the Ti/Ti(Al,Si) 3 interface or within the Ti(Al,Si) 3 layer, as confirmed by its fractured surface. For both infinite and circular paths, fracture occurred in the heat affected zone of Al base metal. Combined interfacial IMC distribution and fractured results, it could be inferred that when Al/Ti interface was bonded with 1.1–3.6 μm Ti(Al,Si) 3 , it had higher bonding strength than heat affected zone of Al base metal. When interface Al/Ti interface was bonded 4.6 μm Ti(Al,Si) 3 , it had lower bonding strength than heat affected zone of Al base metal.