Effect of Ti/Al on Structural Stability and Mechanical Properties of Fe–Cr–Ni–Al–Ti Alloy

Herein, disordered special quasirandom structure models of Fe 20− x − y Cr 5 Ni 7 Al x Ti y ( x , y = 1, 2, 3, 4, 5) are established for the single‐phase austenitic structure of low‐magnetic stainless steel through first‐principles calculations. The alloy volume exhibits linear expansion with increasing Al and Ti content, affected by the combined effects of doping atomic radius and interatomic interactions. The Fe 14 Cr 5 Ni 7 Al 2 Ti 4 alloy demonstrates the smallest volume and higher structural stability. Energy analysis reveals that the total energy, cohesive energy, and formation energies of all systems are negative, confirming the structural stability of the crystals with varying Al and Ti content. With increasing Ti/Al atomic ratios, the bulk modulus gradually decreases, while the shear modulus and Young's modulus increases, suggesting reduced resistance to volumetric deformation but enhanced resistance to shear and tensile/compressive deformation. Low‐magnetic stainless steels with Ti/Al ratios of 1/5, 3/3, and 5/1 are fabricated to verify the calculated results. These alloys maintain stable austenitic structures and paramagnetic behavior, with yield strength, tensile strength, and elongation ranging in 476–834 MPa, 896–1139 MPa, and 14.6–41.2%. Relative magnetic permeabilities are measured as 1.00457, 1.00474, and 1.00557. This study provides theoretical guidance for the compositional optimization and technological development of high‐strength stable austenitic Fe–Cr–Ni–Al–Ti alloys.