Narrow Results

β-NiAl as a promising oxidation resistant coating material due to it high melting point and good oxidation resistant, however it reveals poor cyclic oxidation performance. In this paper, reactive element Dy doped β-NiAl coatings were prepared by electron beam physical vapor deposition (EB-PVD). Dy doping led to the grain refinement microstructure and Dy segregated mainly at grain boundaries. Cyclic oxidation behaviors of the coatings at 1100°C were investigated. The 0.05at.% Dy and 0.1at.% Dy doped coatings exhibited lower oxidation rate and better cyclic oxidation performance, as compared to the undoped coating. The effects of Dy addition on the morphologies and growth mechanism of the oxide scale were discussed.

NiAl has attracted increasing attentions because of its promising potential as protective coating materials for high temperature oxidation resistance. In this paper, Dysprosium (Dy) doped NiAl alloys were produced by arc melting. Cyclic oxidation of the alloys was carried out at 1200°C. The effects of Dy as a reactive element on the microstructure and failure of alumina scales on NiAl were investigated. For the melted alloy, Dy was mainly precipitated along the grain boundary and some within the grains in the form of DyNi₂Al₃ phase. Compared to Al₂O₃ scale formed on the undoped NiAl alloy, the microstructure of the scale was greatly changed and the ridge-like Al₂O₃ scale became less distinct on Dy-doped NiAl. The equi-axed alumina scale grew on NiAl, whereas the columnar alumina developed on Dy doped NiAl. The Dy dopant prevented the oxide scale from rumpling and the formation of cavities beneath the oxide scale. Due to this, the oxide scale adhesion was significantly improved. For Dy-doped NiAl, the scale failure mostly occurred surrounding the oxide protrusions where were rich in Dy.

The effective liquid drop model (ELDM) is used to explore the one proton radioactivity of all possible Dysprosium isotopes, and the molecular phase of the di-nuclear system is used to investigate the possible barriers limiting one proton emission. The mass excess values are obtained from [Chin. Phys. C45 (2021) 030003]. The WKB integral is used to evaluate the penetration probability. The half-lives of proton decay are compared to those of other decay modes. The decay chains of ${}^{133-135}$Dy are predicted. The detailed investigations of ${}^{133-135}$Dy show proton radioactivity when ${}^{133-135}$Tb is converted to ${}^{132-134}$Gd with the half-life of order of nanoseconds. Further, these identified proton emitters may find to be useful in the field of diagnosis and radiotherapy.

Undoped and Dy${}^{3+}$-doped SrS nano-powders were synthesized by a solid-state diffusion method (SSDM). The nano-powders are then examined by the use of characterization tools as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) including selected area electron diffraction (SAED). The emission spectra of SrS: Dy${}^{3+}$ powders are composed of a broadband and the characteristic emission of Dy${}^{3+}$ peaking at 482nm (blue region), 581nm (yellow region), 676nm (light red region) and 750nm (dark red region) bands corresponding to the transitions of ⁴F${}_{9∕2}$-⁶H${}_{15∕2}$, ⁴F${}_{9∕2}$-⁶H${}_{13∕2}$, ⁴F${}_{9∕2}$-⁶H${}_{11∕2}$ and ⁴F${}_{9∕2}$-⁶H${}_{9∕2}$, respectively. The resultant nano-powders can be used to fabricate thin films for the applications of efficient optoelectronic devices.

The NiAl-Cr(Mo) eutectic alloy doped with Dy and B was prepared by injection casting technique and its microstructure and mechanical properties have been investigated. The results exhibit that with the addition of Dy, the Ni₅Dy phase has been formed along the NiAl/Cr(Mo) phase boundaries in intercellular region. Microstructure of the injection-cast alloy gets well optimization, which can be characterized by the fine interlamellar spacing, high proportion of eutectic cell area and fine homogeneous distributed Ni₅Dy phase. Compared with the conventionally cast alloy, the room temperature mechanical properties of the injection-cast alloy get significant improvement, which can be attributed to the fine microstructure, the homogeneous distribution of the Dy elements and the extension of solid solution.