I use my Econotig for general hobby welding, and I occasionally use it for my X-ray repair business. One problem that I recently encountered is I was trying to repair a broken metal bracket that holds a rear cover onto a Dental X-ray tube head. From the look and feel of the metal, I was certain that it was cast Aluminum, but I had a heck of a time trying to Tig weld it. The broken section of the bracket is only about 0.25 in wide by 0.125 in think, and about 3 inches long. The metal seems to be very brittle, as it breaks very easily when flexed even a small amount. When trying to Tig weld it, the metal just melts into a very rough looking blob, and will not accept Aluminum filler rod. After many frustrating attempts, I began to wonder if maybe the metal isn't Aluminum, and is rather Magnesium. So, could anyone please tell me how I could test the metal to determine if in fact it is Magnesium instead of Aluminum? BTW - I'm using pure Argon, with 1/16 inch Thoriated Tungsten.