Exploring the effect of alloying elements on the thermoelasticity and strength of bcc Fe-based alloys by first-principles phonon calculations

Abstract

Designing compositions for novel alloys requires a fundamental grasp of the role of each alloying element in its properties. This study delves into the influence of alloying elements in Ultra-High Strength Steels on essential high-temperature properties, including thermoelasticity, thermal stress, and strength, utilizing first-principles phonon calculations. These properties are pivotal for steels used in high-temperature applications. Our investigation quantitatively forecasts the impact of alloying elements on elastic properties, providing valuable insights for advanced alloy design in high-temperature environments. The introduction of alloying elements markedly amplifies the elastic modulus of Fe-based alloys. The Ni, Mo, Cr, and C elements significantly enhance the anisotropy of the alloy. While refining elastic modulus and mechanical properties, alloying elements induce thermal stress, posing a potential risk of high-temperature cracking. The quantitative analysis underscores the robust strengthening potential for C, Ni, Mo, and W elements, with interstitial C emerging as pivotal in enhancing mechanical properties. The findings of this study illuminate the diverse roles played by different alloying elements and offer theoretical guidance for the design of advanced Ultra-High Strength Steels.

Keywords

• Thermodynamics
• Phonon
• Elastic properties
• First-principles calculations
• Thermal stress