Dwarf star alloy
From Tardis Wiki, the free Doctor Who reference
Dwarf star alloy was an alloy. It was obtained from white dwarf stars. It was the only material that could hold Time-sensitive species
Rorvik's space ship was made from Dwarf star alloy. (DW: Warriors' Gate)
Father of Mine was chained with a chain made from Dwarf star alloy. (DW: The Family of Blood)