Hydrogen solution in tungsten (W) under different temperatures and strains: a first principles calculation study.

Area of Science:

• Materials Science
• Computational Materials Science
• Physical Chemistry

Background:

• Understanding hydrogen behavior in tungsten (W) is critical for fusion energy applications.
• The solution behavior of hydrogen in metals is influenced by various thermodynamic factors.
• First-principles calculations provide a robust framework for investigating atomic-scale phenomena.

Purpose of the Study:

• To systematically investigate hydrogen (H) solution behavior in body-centered cubic tungsten (bcc W) under varying external strains.
• To elucidate the roles of ground state energy, entropy effects (vibrational and configurational), and temperature on H solubility.
• To quantify the impact of tensile and compressive strains on H solution thermodynamics in bcc W.

Main Methods:

• Utilized first-principles calculations to model H-W interactions.
• Analyzed H solution energy, considering lattice ground state energy and entropic contributions.
• Simulated systems under varied tensile and compressive strains and temperatures (300 K to 1800 K).

Main Results:

• Hydrogen solution energy in bcc W is dependent on both ground state energy and significant entropy effects.
• Entropy contributions include lattice vibrations and H configurational distribution in interstitial sites.
• H solubility in W increases dramatically with temperature (from 3 × 10^-18 at 300 K to 1.1 × 10^-3 at 1800 K) and is promoted by tensile strain while suppressed by compressive strain.

Conclusions:

• Temperature is a dominant factor governing H solubility in bcc W due to entropic effects.
• External strain significantly modulates H solution behavior, with tensile strain enhancing and compressive strain reducing solubility.
• These findings are crucial for predicting and controlling hydrogen behavior in tungsten under operational conditions.