From Twinfinite: "If you’re looking to upgrade every weapon to its maximum level in Nier Replicant, then you’ll need to figure out how to gather some of the rarest materials in the game. This is easier said than done, though, as many of these materials only drop from specific enemies under certain conditions. That’s why we’re here to lend you a hand with a guide on how to get Memory Alloy in Nier Replicant.
Before going any further though, it’s worth noting that you won’t be able to make use of the following information unless you’ve reached the second half of the game. If you haven’t reached this point yet, move your focus toward story progression for a bit and then come back to this task."