Taurus ultralite cylinders are titanium, the frames are alloy. They made a couple total titamium, I think they made a 605 all titanium. But the ultralite cylinders can take a brutal beating. I have the .444 ultralite, and have ran some loads through it I wouldn't let a S&W touch.
I guess I should add they do make a small ultralite with a steel cylinder, a version of the 85 I think.