I recently read this in the AWS digest:

One way to gain the benefits of helium without the cost is to use small additions of nitrogen in the argon shielding gas. For example, the addition of 600 PPM of nitrogen to argon for GMAW delivers effects similar to adding ~30% helium to argon. Adding nitrogen to aluminum creates aluminum nitrides, which are highly emissive (because the surface more efficiently emits thermal energy) and can deliver similar results as helium blends at a reasonable price.

Has anyone out there tried this?
It seems go against the normal tide...

Scott Griskavich
Badger welding Supplies