You heard now about aluminum welding alloys that are used to make joints between die-cast, pot metal and al-alloys. Even for professional welders, welding aluminium alloys can present quite a challenge and need expensive welding equipment (read this). The main feature of the material practicality is a low enough temperature (about 380 Celsius ) to avoid recrystallizing the base material. Aluminum welding rod is stronger than base aluminum alloy.
Zn-Al brasing won’t work on ferrous metals except galvanized steel, they also don’t stick to Stainless steel or 2000 grade aluminium, lead and pewter. You need to scrupulously clean aluminum with wire wheel and solvent from oxidized metal, it should be shiny. Heat the area to be weld evenly, and just after it, rub the rod vigorously against the heated piece until the rod flows and wet the base metal.
And some final tips. Pre-tinning helps to achieve best results. Heat and cover with aluminum welding rod both surfaces Remove pores and bubbles with brush, in this case you can use direct flame on alloy. With sides thoroughly tinned, assemble the details and flow in enough rod to fill the vee. Although the use of flux is not necessary, a good paste will make the joint stronger and welding easier (toolsglobe.com/welding/aluminum-welding-rods/).