stainless steel!
I'm currenty working in Qantas flight catering and i can tell you that many carriers use all stainless steel cutlery. Qantas certainly do on some flights.
Some airlines still use stainless steel knives and slowly some airlines are bringing them back in. Qantas ones are amongst the sharpest!
If you refer to my post on Catering in the cabin crew forum I've been asking about the Qantas meal boxes....i'm not sure if the pax like them....I often receive unopened boxes with messages scribbled on top that say..."I would not feed this to my dog etc"