Study on Interface Microstructure and Bonding Properties of Hot-Rolled Nickel-Based Composite Plate

In this paper, the interface microstructure, elements’ diffusion features at the interface, and bonding properties in nickel-based alloy/carbon steel clad composite prepared by vacuum hot-roll bonding were investigated, comprehensively. The influence of element distribution on the interface bonding strength was revealed as well. The results showed that there was a 13 μm thick diffusion layer at the interface of nickel-based alloy/carbon steel composite plate, which was beneficial to a strong bond between nickel-based alloy and carbon steel, as well as the stable transition of mechanical properties in the thickness direction. Kirkendall voids and fine-grained structure (the grain size is about 41.5 nm) were observable by peeling off the nickel-based alloy cladding, which greatly promoted element diffusion and enhanced the interfacial bonding strength of the nickel-based alloy/carbon steel composite plate. The diffusion coefficient of Ni at the interface was about 2 orders of magnitude larger than that of nanocrystalline Fe. The shear strength reached up to 453 MPa, which was much higher than the minimum of 140 MPa defined in ASTM A-264 specifications. Furthermore, in the shear test, the fracture occurred on the X52 carbon steel side at the contact rather than at the composite plate interface.

Engineering of Fe-pnictide heterointerfaces by electrostatic principles

Interface-related phenomena have great potential to control the superconducting state in Fe-based superconductors. We propose a comprehensive classification of Fe-pnictide heterointerfaces based on electrostatic principles that allow the prediction of the interface microstructure, in particular, distinguishing between clean heterointerfaces and the formation of interfacial layers. The concept was successfully tested on a novel LnOFeAs/BaFe2As2 (Ln = La, Sm) Fe-pnictide heterostructure. With the addition of different cations/anions, it is possible to produce clean interfaces or interfacial layers. The impact of the microstructure on superconductivity in the Fe-pnictide heterostructures is discussed.