The density of TI is .17 lbs. per cu. in., so if you made a panel .032 thick that was 6' X 3' in area, the panel would weigh 14.1 lbs.

If the same panel were made in .040 AL, it would weigh 10.16 lbs.

So there is no advantage to building a firewall from TI, unless you have some free sheets and access to carbide cutters and bits.