Extended Data Fig. 1: Complementary plot supporting the kinetic conception.

Following the thermodynamic guideline discussed in main text Fig. 1b, the oxide reduction complete temperatures^51,52,53 for Fe, Cu, Ni, and Co are compared with the bulk melting points. It is evident that for all these four elements, the corresponding oxides reduction by H₂ completes below \(0.75\,{T}_{{\rm{m}}}\), i.e. the homologous temperature at which significant densification takes place³⁵.