Leading edges of the wings, horizontal stabiliser, vertical stabiliser and the engine’s inlets are producted from aluminum.
As you know, there is a risk of bird strikes for airplanes in all flight operations. Metal parts tend to be more resistant to impact, while composite materials tend to be weak and delaminate. In addition, metal parts can protect their strength against impacts. Similar features can be said for hail as well as bird strikes. When you look at bird strike examples, you will see that composite materials are damaged more than metal.
There is a weather radar in the nose of modern passenger planes. At this point, the use of metal material can block the radar waves. Therefore, composite material was preferred for radome production.
Another reason for using aluminum is to prevent icing on the leading edge. Disruption of air flow at the edge of attack and engine inlet adversely affects flight safety and performance. For this reason, there are ice anti icing systems in critical areas of the aircraft.
The leading edges of the wings and the engine inlets are heated by the bleed air taken from the engine (or, for the 787, electrical elements). As you can imagine, metal materials conduct heat better than composites.
In addition to all these, shaping metal is much easier and more economical than shaping composite. With the development of composite materials, we can say that the use of composites in all parts will increase over time.
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