Elon Musk could utilize metal hot structures for rocket re-entry. This is a decades old idea. I don’t think it has been utilized in trip since the early X-plane program days. There has been more lab and ground experiments on the ideas.
This could be another bold innovation decision for SpaceX to indeed attack the NASA warehouses of promising however immature innovation. The X-planes did not achieve orbit and did not re-enter from orbit. Elon Musk and SpaceX plan to have the Super Heavy Starship re-enter Earth and Mars at far higher speeds than have been tried previously. These requests will put more pressure and warmth on the rocket.
Elon has tweeted that the updated Super Heavy Starship (otherwise known as BFR) would utilize a great deal of metal in the design. He said it would be a radical counter-intuitive design. He referenced that the tanks, airframe and heatshield were updated yet the shape or counters would be generally the equivalent. In September when Elon was reporting the Japanese billionaire, he indicated reenactments demonstrating the BFS re-entering unpowered like a human parachutists previously the parachute opens. SpaceX Starship needs to come in quick, unpowered and make due for the arranged a large number of re-utilizes with preferably no maintenance.
I am going to make the estimates on the material. I think Titanium alloy or nickel alloy for the hot metal structure will be utilized in the Super Heavy Starship. We will presumably get affirmation in January 2019 when pictures and data could be released.