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Interfacial atomic configuration plays a vital role in the structural stability and functionality of nanocomposites composed of metal nanoparticles (NPs) and two−dimensional semiconductors. In situ transmission electron microscope (TEM) provides a real−time technique to observe the interface structure at atomic resolution. Herein, we loaded bimetallic NiPt truncated octahedral NPs (TONPs) on MoS2 nanosheets and constructed a NiPt TONPs/MoS2 heterostructure. The interfacial structure evolution of NiPt TONPs on MoS2 was in situ investigated using aberration−corrected TEM. It was observed that some NiPt TONPs exhibited lattice matching with MoS2 and displayed remarkable stability under electron beam irradiation. Intriguingly, the rotation of an individual NiPt TONP can be triggered by the electron beam to match the MoS2 lattice underneath. Furthermore, the coalescence kinetics of NiPt TONPs can be quantitatively described by the relationship between neck radius (r) and time (t), expressed as rn = Kt. Our work offers a detailed analysis of the lattice alignment relationship of NiPt TONPs on MoS2, which may enlighten the design and preparation of stable bimetallic metal NPs/MoS2 heterostructures. [ABSTRACT FROM AUTHOR]

Herein, the microstructure stability of a newly developed hot‐working die (HWD700) steel at elevated temperatures up to 700 °C is investigated using transmission electron microscopy (TEM), selected‐area electron diffraction, energy‐dispersive spectrometer, and high‐resolution transmission electron microscope. The results show that the HWD700 steel exhibits a higher thermal stability than the commercial H13 steel when the temperature is up to 700 °C. After quenching and tempering, high densities of intra‐lath rodlike and inter‐lath spherical MC nano‐carbides and inter‐lath strip‐like M7C3 nano‐carbides are observed in the HWD700 steel. These carbides remain nanoscale at temperatures up to 700 °C. For comparison, rod‐shaped MC nano‐carbides in the tempered H13 steel tend to coarsen and transform into larger M23C6 carbides at temperatures up to 650 °C. The TEM observation further reveals that the interface misfit between the MC nano‐carbide and matrix in the HWD700 steel is as low as 0.88%, lower than that of 14.8% in the H13 steel. This can be the main reason for the improved stability of the HWD700 steel by pinning dislocations and grain boundaries and thereby hindering the recrystallization process at an elevated temperature. [ABSTRACT FROM AUTHOR]