Configurational Entropy Effect on Thermal and Mechanical Properties of Pt1Pd1Rh1Co1 and Pt41Pd18Rh5Co32 High‐Entropy Alloys

• Published in: physica status solidi (b) Vol. 260; no. 4
• Main Authors: Ju, Shin-Pon, Lee, I-Jui, Li, Chen-Chun, Shih, Huai-Ting, Wang, Wen-Zhi
• Format: Journal Article
• Language: English
• Published: 01-04-2023
• Subjects: configurational entropy effects; high-entropy alloys; molecular dynamics simulations; second-nearest-neighbor modified embedded‐atom‐method potential; thermal and mechanical properties
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.202200366

The configurational entropy effect on thermal and mechanical properties of Pt1Pd1Rh1Co1 and Pt41Pd18Rh5Co32 face‐centered cubic high‐entropy alloys is investigated by the molecular dynamics simulation with the second‐nearest‐neighbor modified embedded‐atom‐method potential. Using the heating process, 3000 and 2375 K are melting temperatures (Tm) of Pt1Pd1Rh1Co1 and Pt41Pd18Rh5Co32. Local structures around Co atoms become more distorted above 2425 K (about 0.81Tm) for Pt1Pd1Rh1Co1 and 1325 K (about 0.56Tm) for Pt41Pd18Rh5Co32. The Arrhenius equation shows that diffusion barriers of all element types in Pt1Pd1Rh1Co1 are about 50–89% higher than those in Pt41Pd18Rh5Co32, and the pre‐exponential factors of Pt1Pd1Rh1Co1 are about one order higher than those of Pt41Pd18Rh5Co32. Using the uniaxial compression simulation, the ultimate and yielding stresses of Pt1Pd1Rh1Co1 are about 88.3% and 53.4% higher than the corresponding values of Pt41Pd18Rh5Co32. For Young's modulus, Pt1Pd1Rh1Co1 is about 34.8% higher than that of Pt41Pd18Rh5Co32. At the yielding strain, the dislocation extraction algorithm results show that no local defected structures appear within Pt1Pd1Rh1Co1, whereas several nanoclusters of defected structures distribute randomly within Pt41Pd18Rh5Co32. At ultimate strain, multiple Shockley partial dislocations nucleate from the free surfaces for Pt1Pd1Rh1Co1, and more nanoclusters of defected structures appear within Pt41Pd18Rh5Co32, where Shockley partial dislocations nucleate.
The molecular dynamics simulation using second‐nearest‐neighbor modified embedded‐atom‐method potential is used to explore the thermal and mechanical properties of Pt1Pd1Rh1Co1 and Pt41Pd18Rh5Co32 high‐entropy alloys (HEAs) by the heating and compression processes. The melting behaviors and the mechanical properties of these two HEAs are investigated by the square‐displacement profiles and by the stress–strain curves, respectively.