Exploring nanocomposite filler rods for welding of high strength Al-Zn-Mg alloys

Project description

The 7xxx Al alloys (Al-Zn-Mg-Cu) alloys offer exceptional strength to weight ratio advantage and are of great interest in the aerospace industry where structural light-weighting is demanded. However, joining of these materials is known to be highly challenging susceptibility toward hot-cracking during welding. This acts as a barrier for wider use of such greatly attractive alloy class. The aim of this project is to study the possibility of welding high strength Al 7xxx series alloy, which are one of the difficult alloys to weld. The chosen alloys for the study would be Zr-containing high strength AA7055 and AA7068 alloys. In this vein, we aim to design and develop a novel filler alloy composition. This filler alloy is envisaged to be a nanocomposite with Al-alloy matrix and ceramic nanoparticle dispersion. And using the nanocomposite filler rods, welding trials would be carried out to demonstrate the weldability of the Al 7xxx series alloys. Firstly, for processing of these filler rod compositions, the stir casting route would be pursued. A major component of the design specification would be to achieve a uniform dispersion of the ceramic nanoparticles as opposed to their local agglomeration in the microstructure, that would result in isotropic property attributes to the components. Solely for the purpose of comparison a single batch of the bulk composition would also be fabricated by powder bed fusion (selective laser melting) additive manufacturing route. Secondly, once the nanocomposites are fabricated by the above processes, the bulk material is to be extruded into the filler rods for welding. In this regard, processing window for the composites to be extruded into rod forms would be assessed and identified. Thirdly, the possibility of welding using these manufactured filler rods would be evaluated. using conventional fusion arc welding process such as tungsten inert gas (TIG) welding.

Outcomes

1. To study the possibility of welding high strength Al 7xxx series alloy, through the design and development of nanocomposite filler alloy with Al-alloy matrix and ceramic nanoparticle dispersion.
2. One patent
3. 3-6 papers in international peer-reviewed journals.

Essential capabilities

Sound knowledge in materials science and engineering

Desireable capabilities

Basic knowledge on alloy design

Expected qualifications (Course/Degrees etc.)

Bachelor with first class honors or equivalent