There's a whole list of mythological and fantasy metals, but for the sake of a scenario where iron has never been used to make weapons, armor, prison bars or even construction, let's focus on just these three instead:
- Orichalcum: Invented in Plato's Atlantis, it's described as being bronze or copper in color. Properties vary from source to source, the most realistic being strength and high value. So, feasibly, this could be a suitable fantasy or alternate-history alternative to bronze, which dominated human culture from the third millennium BCE to only the fourth century BCE
- Adamantium: A very popular metal or alloy, its basic recurring property is that it is harder, stronger and more resilient than diamond.
- Hihi'irokane: The Japanese equivalent of orichalcum, first invented in the 1930s. Its most realistic properties are being rustproof and ultra-hard.
So with these details in mind, in a scenario in which these fantasy metals are actual alloys, what would they be made from based on the properties?