Material Array Fading

Hey there,

I am a student artist working on an in house uni game project with a team for our final year.

The question I have is can a material array have a fade out/in sequence with the set materials with in it.
Currently I have two materials, one diffuse and one translucent which acts as the cloak/invis for our character bound to a key press in the character actor material array. Can I achieve a fade out and in effect for switching between these two materials on key press through the array, or is there a better way of doing this? If so how?

Many thanks for any input or answers.