Throttle vales and materials

Good day motorsports enthusiasts,

Does anyone know the materials used for the manufacture of throttle bodies and adapters on diesel engines? I am trying to find the materials and processes used, as well as the effectiveness of these and the costs involved. I am particularly interested on FORD diesel engines. Your help will be much appreciated as this investigation is part of the research for one of my university modules. Thank you.

Regards

giogar