A cost-effective iron-rich medium entropy alloys with the balance of strength and ductility

• Published in: Vacuum 2024-10, Vol.228, p.113506, Article 113506
• Main Authors: Zheng, Zehong, Shen, Qingkai, Yu, Xiaoyan, Ou, Ning, Dong, Changwen, Li, Jin, Zhu, Qiang, Xue, Jiaxiang
• Format: Article
• Language: English
• Subjects: CALPHD; Eutectic high-entropy alloys strategy; Iron-rich medium-entropy alloys; Metastability-engineering strategy; Precipitation strengthening
• ISSN: 0042-207X
• DOI: 10.1016/j.vacuum.2024.113506

Iron-rich medium-entropy alloys (MEAs) have attracted attention due to the balance for cost and properties of alloy. In this study, a combined metastability engineering and eutectic high-entropy alloys (EHEAs) design strategy were employed to develop a cost-effective, iron-rich MEAs for the Fe–Cr–Ni–Al MEAs system using CALPHAD simulations. This approach enabled the tailored control of soft and hard phases within the non-isoatomic MEAs system by manipulating the elemental ratios. Specifically, increasing the aluminum (Al) content promoted the stability of the BCC/B2 phase, and the microstructure of the MEA transitioned from a single-phase FCC structure to a mixed FCC + BCC/B2 structure, culminating in a final single-phase BCC/B2 structure. This BCC/B2 phase precipitation strengthening mechanism led to enhanced microhardness and yield strength in MEAs with high Al content. Notably, the Al11-as alloy demonstrated a yield strength of 692.7 ± 30.4 MPa (precipitation strengthening is ∼428.98 MPa, accounting for the true yield strength of the alloy ∼61.9 %), with an ultimate tensile strength reaching a maximum value of 992.3 ± 32.77 MPa. Moreover, the alloy retained a satisfactory elongation of 7.1 ± 2.9 %. These efforts hold promise for the development and application of cost-effective, iron-rich MEAs for the Fe–Cr–Ni–Al MEAs system. •A cost-effective, iron-rich MEAs for the Fe–Cr–Ni–Al MEAs system using CALPHAD simulations.•Thermo-dynamic phase calculation proves to be a valuable tool for MEAs design and phase prediction.•The tailored control of soft and hard phases within the non-isoatomic MEAs system by manipulating the elemental ratios.•Precipitation strengthening plays a significant role in enhancing the overall strength of the Fe57.88(CrNi) (42.12-x)Alx MEAs.