C-17 still has alum wings, but years ago it did switch to a carbon horizontal tail.
I remember what a big controversy there was prior to mass production, when the carbon fiber wings were being tested. I lived near Charleston AFB, and anything concerning C-17s was always big news. I specifically remember the carbon fiber wings had trouble with some static load tests. At the time, the plane was being touted as containing more carbon fiber than any other aircraft to date. That is my memory....