Windows/Steam Version 0.51
I started a new save file in 0.51 for testing
I have found obtained 4 Legendary Artifact Materials [Trait Slot Materials] in 5 Realms. (One each in the first three realms).
I have played through the early game many times and this seems way out of line for what I found prior to 0.5. This could just be a random coincidence (some players will get crazy random streaks), but if you altered drop rates at all in 0.5, you should consider double-checking to make sure that Legendary materials aren’t dropping more often than intended.