University of Science and Technology Beijing

About: University of Science and Technology Beijing is a education organization based out in Beijing, China. It is known for research contribution in the topics: Microstructure & Alloy. The organization has 41558 authors who have published 44473 publications receiving 623229 citations. The organization is also known as: Beijing Steel and Iron Institute.

Synthesis and characterization of refractory TiZrNbWMo high-entropy alloy coating by laser cladding

Abstract: A novel refractory high-entropy alloy (HEA) coating with composition close to TiZrNbWMo was synthesized on 45 # steel by laser cladding. Constituent phases, microstructure, chemical composition and microhardness of the coatings before and after annealing were investigated by XRD, SEM, TEM, EDS and micro/Vickers hardness test, respectively. Results showed that the TiZrNbWMo coating was ~ 513 μm in thickness. The microstructure of the coatings exhibited typical dendritic and interdendritic structure. The coating was composed of a major body-centered cubic (BCC) solid solution and a small amount of β-Ti x W 1 − x precipitated phase due to high-entropy affect and laser rapid solidification. Apart from enhanced fraction of β-Ti x W 1 − x precipitation, the structure and BCC solid solution phases remained almost unchanged after annealing at 800 °C, 1000 °C, and 1200 °C for 20 h, indicating that the coating had high thermal stability. The microhardness of as-clad HEA coating reached around 700 HV 0.5 , which was three times of 45 # steel substrate. The coating microhardness increased significantly after annealing, which was due to the solid solution strengthening of BCC matrix and formation of β-Ti x W 1 − x precipitation. Notably, the highest value was up to 1300 HV 0.5 after heat treatment at 800 °C. Therefore, the HEA coatings showed high microhardness and resistance to softening.

CH3NH3PbBr3 Perovskite Nanocrystals Encapsulated in Lanthanide Metal-Organic Frameworks as a Photoluminescence Converter for Anti-Counterfeiting.

Abstract: The increasing demands for optical anti-counterfeiting technology require the development of versatile luminescent materials with multiple models and tunable photoluminescence. Herein, the combination of luminescent perovskite nanocrystals and lanthanide-based metal–organic frameworks (Ln-MOFs) has been developed to offer such a high-tech anti-counterfeiting solution. The hybrid materials have been fabricated via the encapsulation of perovskite CH3NH3PbBr3 nanocrystals in europium-based metal–organic frameworks (Eu-MOFs) and they display multistage anti-counterfeiting behavior. CH3NH3PbBr3@Eu-MOF hybrids were developed in a two-step process, where the PbBr2@Eu-MOF precursor was formed first and, then, the composites can be formed quickly by the addition of CH3NH3Br into the precursors. Accordingly, the hybrid composites exhibited both excitation wavelength and temperature-dependent luminescence properties in the form of powders or films. Furthermore, the photoluminescence of the CH3NH3PbBr3@Eu-MOF composi...