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• The interaction between 27 transition metals, O and vacancy in Mo are implemented by first-principles calculations. • The interaction between solute and O can be accurately separated into elastic and chemical contribution. • Simonovic's model indicates dilute TMS atoms can capture O and inhibit the enrichment of O in Mo. • Solute Sc, Ti, Zr, Hf, and Ta can be the top priority to inhibit O segregation and embrittlement in Mo alloys. The trapping effect of solute on oxygen (O) can be benefit for inhibiting its segregation and embrittlement at the GBs in Mo alloys. In this work, the interaction between solutes (including 27 transition metals), interstitial O and vacancy in Mo are implemented by first-principles calculations, and their trapping effects on O are evaluated by Simonovic's model. Single transition metal solute (TMS) has a strong attraction for O, and it is strengthened by the second solute for all 3 d , oversized 4 d and 5 d series. Furthermore, there is a significant synergistic effect between solute, vacancy, and oxygen for oversized solutes, i.e., the binding energy between solute atom (vacancy) and oxygen atoms is enhanced by the presence of vacancy (solute). The distribution of oxygen indicates that oxygen can be captured by dilute TMS atoms, and more oxygen atoms will be trapped as the solute concentration increases in Mo. Based on our extensive calculations, Sc, Ti, Zr, Hf, and Ta can be the top priority for suppressing the segregation and embrittlement of O in Mo alloys. It is interesting that the interaction between solute and O can be accurately separated into elastic and chemical contributions though delicate calculation, and the counterintuitive strong binding effect of fifth-nearest solute-O pairs for undersized 4 d and 5 d elements is owning to the chemical contribution driven by Coulomb interaction. [ABSTRACT FROM AUTHOR]

Uranium is an important strategic metal widely applied in the nuclear industry. Using first-principles calculations, we investigated the plane slip properties, anisotropy, and bonding characteristics between atoms of α -uranium. We found that the DFT+ U has limited effect on elastic constants and the generalized stacking fault energy of α -uranium, although it includes 5 f electrons. Then we calculated the elastic constants and shear deformation properties using standard DFT, and found that the energy barrier of plane slip of α -uranium is arranged from high to low as: (010)[001] > (100) [ 010 ] > (100)[001] > (001) [ 010 ] > (001) [ 100 ] > (010)[100], which perfectly supports the assumption of wrinkled quasi-atomic planes. At last, electronic structure calculations reveal that the wrinkled strong quasi-atomic planes are composed of metallic bonds with partial covalent character. [ABSTRACT FROM AUTHOR]

[Display omitted] The point defect properties of body-centered cubic medium-entropy alloy NbZrTi were studied by first-principles calculations. Due to severe lattice distortion, a significant portion of conventional vacancy and interstitial structures are unstable and require large structural relaxation, indicating an irregular energy landscape with large site-to-site variations. The average vacancy and interstitial formation energy are 0.95 eV ± 0.34 eV and 1.92 eV ± 0.39 eV, respectively, much lower than that of Nb (2.77 eV and 4.38 eV). The vacancy migration energy exhibits a wide distribution extending to 0 eV, resulting in preferential vacancy migration through low barrier sites. The interstitial diffusion is slower than that of pure Nb due to the reduction of long <111> diffusion induced by the site-to-site variations in stable interstitial orientations. Ti atoms diffuse much faster than Nb and Zr atoms due to the preferential interstitial binding with Ti. The effect of atomic composition and short-range order on elemental and total interstitial diffusion was also investigated. The obtained first-principles results are important for the development of interatomic potentials for radiation damage studies. When irradiated with 3-MeV Fe ions at 675 ∘ C to a peak dose of ∼ 100 dpa, NbZrTi reduced the void formation at high temperature compared to Nb owing to its higher equilibrium vacancy concentration and closer mobility between vacancies and interstitial atoms. [ABSTRACT FROM AUTHOR]