While researching turrets, I would choose 5 of the same type. The outcome would be the same material, but the glow would be yellow. I researched 5 titanium tesla turrets, the outcome was a titanium material, but has a yellow glow. The turret can only be placed on titanium and above. See screenshots below. Happened with other material types too.
http://imgur.com/a/deCGE
This also happened with mixed material types of the 5 items to be researched. The outcome material would have the wrong glow.