Alloy first appears in the alternate future of Earth-22, one of the 52 Earths in the DC Multiverse. Alloy is the combination of all five Metal Men into one being. The being survives Captain Atom being split by the Parasite, making it one of only two survivors of the incident. Alloy reappears throughout the story as a member of Superman's group, culminating in the assault at the Gulag that is built. After the area is bombed by the UN, Alloy is destroyed. The last that is seen of it is its mostly melted body.
Alloy appeared for the first time in standard DC continuity during the DC One Million, during which the Metal Men are infected with the Hourman Virus. The Metal Men combine into Alloy to fight Superman. It appeared again when the Metal Men were captured by Max Lord and they were forced into battle against the Justice League International.
Batman: Brave and the Bold
Alloy appears in the episode "The Coming of Starro! Part 2". After Starro is mutated by the Faceless Hunter using B'Wana Beast's powers, the Metal Men transform into Alloy to fight the massive Starro beast. After dealing blows and being dealt blows, the robot is beaten into the harmonic tower the beast needs to crack the planet. Batman is able to disable B'wana Beast's trap, though, and Alloy is able to beat Starro back into the probes that made it up.