Tironium

Tironium is an extremely tough, ultra-light metal.

Fiction

Beast Wars cartoon

Upon observing Terrorsaur after he absorbed unstable energon into his superstructure from the flying mountain, Rattrap commented that, with his newfound power, the Predacon looked like he could "eat tironium". Power Surge

Animated

Megatron's two swords are made of trionium, an ultra-light metal developed by Sumdac Systems. Transformers Animated: The AllSpark Almanac