This I can answer with some authority.
I'll start by expanding on Hawks answer
|Quoting HAWK21M (Reply 7):|
Turbine & high temperature sections can use Titanium alloy.
Fan cases can be aluminum alloy,Graphite Epoxy.
Kevlar Epoxy & other Fibreglass for other Areas depending on Temperature requirements.
Low Compressor blades and rotors: Titanium. Low compressor blades could be aluminum, but no one wants to be the first to see how much quicker the softer metal wears than titanium.
High compressor: last stages of high compressor the blades must be nickel alloy. Earlier might be titanium. Too hot for Aluminum.
Nacelle: mostly Aluminum. Near compressor surge vents some titanium on certain engines.
Fan shroud: Aluminum with Kevlar overwrap around fan containment area. Fan guide vanes are usually aluminum too.
Turbine exhaust area of nacelle... will have to be a higher temp alloy. Since I don't know *exactly*, I'll punt this part. With temperatures could just be 316L, but this is my one guess.
Case: Inconel 71X family. (Pretty standard in the industry is Inconel 715, but not always) Needs to be Inconel family due to high combustor inlet temperatures.
Combustor sheet metal (cold side) almost always Inconel 625
Combustor hot side (panels): Either Hastalloy X or Haynes 230 or other proprietary metal (e.g. pwa1422).
Fuel injector stems: Usually Inconel 625, but I've seen other nickels.
Tubine inlet vane/high turbine: vendor proprietary single crystal nickel.
Turbine rotor: One of the few areas where cobalt based alloys still predominate, but I've seen Nickel ones too.
Low turbine: usually directionally solidified Nickel alloys (Crystals directionally aligned).
Once upon a time I even knew what the shafts were made from... but I cannot recall tonight.
Why all the different materials? Weight and cost. Single crystal nickel is about 3X
the cost of directionally solidified nickel. Directionally solidified nickel is much more than regular vacuum cast nickel. Titanium is light, but pricey. Aluminum is cheap and fairly light. In newer engines expect to see more composites (e.g., aluminum in the fan shroud replaced with carbon fibre). Some materials are selected because they cast well (Inconel 715, Inconel 625), some because they are easy to form in sheet metal (Aluminum, Inconel 625), some for weldability, and some for their properties at high temperature.