Transformation-induced plasticity (TRIP) in ductile iron and resultant exceptional strength-plasticity synergy

This study produces a Ni-containing ductile iron with a matrix consisting of lamellar α and γ phases, along with nanoscale Mg₆Si₇Ni₁₆ phases. The interface of fine α and γ phases and the nanoscale Mg₆Si₇Ni₁₆ phases impede dislocation mobility, contributing to high yield strength. During the tensile test, the transformation-induced plasticity (TRIP) phenomenon is etected because Ni addition effectively endows appropriate carbon concentration in γ phase of ductile iron. The TRIP effect significantly augments the strain-hardening capacity of ductile iron, resulting in an excellent plasticity with an elongation of ∼21 % and a considerable ultimate tensile strength of ∼900 MPa. Consequently, the ductile iron achieves an exceptional strength-plasticity synergy, characterized by the product of tensile strength and elongation (PSE) of 19 GPa%.