Aluminum is actually quite easy to weld, just need the right welding rod. CI however, is a real PITA to weld. You most definitely need the correct welding rod plus, the CI should be preheated to prevent cracks from forming.
***Please fill in your profile, at least your location. As this will help us help you better.***
"Whether active duty, retired, national guard or reserve - is someone who, at one point in their life, wrote a blank check made payable to "The United States of America", for an amount of "up to and including my life". That is HONOR, and there are way too many people in this country who no longer understand it." -Author Unknown