Aluminum Grain Refinement via Titanium-Boron Additions

Titanium-boron additives are the usual way to refine the grain of aluminum melts. You add them to the melt so that many small crystals form during solidification and the structure becomes uniform. This benefits strength and also crack resistance when welding. If you use too much or don't stir it in properly, you get lumps and an inconsistent structure, which you don't want. So: weigh it out precisely and distribute it well in the melt, then it's fine.