The scratches on the backs of several of the new iPhone models has nothing to do with aluminum vs titanium. The backs of the corresponding previous models weren't titanium, they were glass, and they seemed to have had their color applied to the inside surface of the glass that you can't touch, and so you can't scratch it. The backs on the corresponding new models are partly glass, but the color seems to have been applied to the top surface of the glass, and partly aluminum, but the anodization process for the aluminum is performing as if it wasn't as high a grade of anodization as it should have been. It's a short matter of time before similar scratches start to appear on the other anodized areas of the housing. While the Deep Blue model seems to be scratching more, the Cosmic Orange models are also scratching somewhat.
Apple says the scratches on the backs of the store display iPhones have been caused by the Magsafe charger stands that the display models in the stores are placed on. I looked carefully at those charger stands in my local store, and as usual, the circumference of the charging/mounting puck doesn't have unusually sharp edges, and it's chamfered (beveled?). It's apparently aluminum though, and being a metal edge, it's conceivable that it could be scratching the backs of the store display models, especially when customers don't place the iPhones back onto these pucks carefully but instead scrub them around until the magnets stick. In my local Apple Store, I found there was something weird about many of these display stands that, as careful as I was, still often forced me to have to do this scrubbing action before the magnets would lock in. It seemed that sometimes this was because some of the new iPhones are so long that their bottom end would hit the base of the display stand as I was trying to place the phone back onto the stand, and this prevented me from easily moving some of these iPhones back onto the puck.
Maybe these are display stands designed for earlier iPhone models with different dimensions? Most non-Apple charging stands I've seen, though there are plenty of exceptions, aren't just a circular puck with its circumference exposed, but more of a puck embedded in a larger surface, usually a square, and maybe this design will prevent scratching from these chargers. Maybe this is what Apple should adopt in their stores.
