Hi, new to the forum and not sure I posted this in the right space.

I just recently purchased a Bianchi Via Nirone 7 Grx400 and I’m very excited.

I noticed in the technical specifications that the frame was listed as “ VIA NIRONE 7 ALL ROAD alloy, TC18,”

At other sections of the specs when describing the Aluminum it is listed as Aluminum Alloy 6061 such as the seat seatpost, handlebars, stem etc.

My question is why did they list TC18 as an alloy for the Bike frame? I can’t imagine the entire frame is titanium but was hoping to learn what part might be or any explanation for the use of the term TC18.

Thanks.