Probing the mechanical properties of ordered and disordered Pt-Ir alloys by first-principles calculations

• Published in: Physics letters. A 2021-07, Vol.405, p.127424, Article 127424
• Main Authors: Zhou, Yunxuan, Chong, Xiaoyu, Hu, Mingyu, Wei, Yan, Hu, Changyi, Zhang, Aimin, Feng, Jing
• Format: Article
• Language: English
• Subjects: First-principles calculations; Mechanical properties; Platinum-iridium alloys; Special quasirandom structures; Virtual crystal approximation
• ISSN: 0375-9601; 1873-2429
• DOI: 10.1016/j.physleta.2021.127424

Platinum-iridium (Pt-Ir) alloys are promising superalloys and widely used as bond coating in aero-engines due to its high melting point, outstanding oxidation resistance and excellent corrosion resistance. As solid solution alloy, the mechanical properties of disordered Pt-Ir alloys are calculated with the special quasirandom structures and virtual crystal approximation methods based on density functional theory. Phonon spectrum shows that the ordered and disordered Pt-Ir alloys are all dynamically stable phases. The calculated lattice parameters, elastic constants and modulus of Pt-Ir alloys are in good agreement with the experimental values. The results show that the bulk modulus, shear modulus, Young's modulus are increasing with the increase of Ir content, while B/G and Poisson's ratio decrease. Moreover, the model of the elastic properties is built based on the CALPHAD approach as a function of chemical composition. The electronic basic of mechanical properties are probed by electronic density and weighted mean bond population. •The Pt-Ir alloys are explored systematically with SQS, VCA and ordered methods.•The thermodynamic stable phases of Pt-Ir alloy are confirmed by phonon spectrum.•The model of the elastic properties is built based on the CALPHAD approach.