Enhancing mechanical properties of high Cr dual-phase FeCrNi medium-entropy alloy through mutual phase transformation and grain refinement

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2024-08, Vol.907, Article 146745
• Main Authors: Hu, Zhaohui, Lin, Yating, Zhang, Lu, Wang, Anguo, Wang, Junyang, Zhang, Rui, Cai, Minghui, Yu, Jianxin, Wu, Baolin
• Format: Article
• Language: English
• Subjects: Dual-phase; Heterogeneous structure; Mechanical property; Medium entropy alloys
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2024.146745

A high Cr Fe40Cr40Ni20 (at.%) medium-entropy alloy was prepared through vacuum arc melting. The alloy exhibited a dual-phase structure comprising face-centered-cubic (FCC) and body-centered-cubic (BCC) phases in a solid solution state. After annealing and cold rolling, two different heterogeneous structures emerged from the original FCC and BCC phases through mutual phase transformation. Moreover, the alloy exhibited a yield strength, ultimate tensile strength, and total elongation of 1.18 GPa, 1.25 GPa, and 13 %, respectively. The high strength of the alloy was mainly attributed to boundary strengthening and heterogeneous deformation-induced (HDI) strengthening within the two heterogeneous structures. Notably, the effectiveness of HDI strengthening was enhanced owing to the complete encapsulation and constraint of soft zones by hard zones in the heterogeneous structure originating from the BCC phase. Additionally, the deformation ability of the alloy mainly depended on dislocation slips and deformation twinning in recrystallized FCC grains and FCC strip phases, thereby ensuring satisfactory ductility. •An ultra-high-Cr alloy with excellent mechanical properties.•Two different heterogeneous structures via rapid-heating annealing.•Strengthening and deformation mechanisms of these heterostructures were investigated.•HDI strengthening was enhanced by the hard phase enveloping the soft phase heterostructure.•The deformation of twins was observed in the micron FCC phase grain.