Disperse ferrite is generally embedded in lightweight steel
yet exhibits decent performance
thereby prompting a question: can heterogeneous design optimize it? Here
two representative structures
featured with discontinuous fibrous and dispersed ferrite separately embedded in the austenite matrix
were constructed as examples to address the issue. A heterostructure with fibrous ferrite shows a remarkable product (49 GPa·%) of ultimate strength and total elongation
standing out among other lightweight steels. Superior strength-ductility synergy is primarily attributed to hetero-deformation-induced strengthening and hardening. Abundant hetero-interactions imparted by phase boundaries
dense slip bands in austenite and dislocation networks inside ferrite serve as underlying physical mechanisms.