Adamantium is a material commonly associated with the iconic Marvel mutant, Wolverine. It's the material infused into his bones that's responsible for his distinctive "metal" claws as well as for slowly killing him. But, while the said material has appeared in the comic books and FOX's X-men universe, it technically isn't a part of the Marvel Cinematic Universe. But, if we believe the recent reports, Marvel Studios will finally bring the fictional metal alloy and it won't be too far off.
According to a new report by Daniel Richtman, Captain America: New World Order, which is on the tail end of Phase 5 of the MCU, will feature an "international conflict over a new metal called Adamantium". The same source claims that the metal will be found on Tiamut Island. This is the name given to the island formed following the failed birth of the Celestial seen in the 2021 MCU film, Eternals.
Apparently, Tiamut Island will answer the glaring question on everyone's minds following the end of Eternals as "every country" reportedly wants a "piece of that new metal."
Assuming that the MCU will avoid any mention of Tiamut Island until then from now (and that the report is true), this will mark the second time that the MCU has addressed that the Celestial exists. The fossilized humanoid indirectly appeared in an episode of She-Hulk: Attorney at Law as an Easter Egg. However, this involvement is more significant and could possibly hint at a larger role of the mutants in the Marvel Cinematic Universe.
Marvel Studios has had to make several creative if ingenious choices to find ways to include certain details into the live-action cinematic universe from the source material that it can't use. For example, Captain America's shield isn't made out of Adamantium but Vibranium in the MCU. But, if we believe that Adamantium will be introduced in Captain America 4, then the MCU might fix this "error" and give Sam Wilson an Adamantium shield.
Coincidentally, Captain America: New World Order premieres on May 3, 2024, just months ahead of Deadpool 3's release on November 8 later in the same year.
If we assume that the production timeline goes well, Marvel Studios could tease Wolverine's arrival in the post-credits scene for Captain America: New World Order or in Thunderbolts.
Speaking of timelines, Hugh Jackman confirmed that the events of Deadpool 3 will happen before Logan. Also, the Wolverine actor has confirmed that Deadpool 3 will feature time-travel. Jackman is currently training for Deadpool 3, which will see him star alongside Ryan Reynolds. Finally, Captain America 4 will start filming early next year.