Plan-view characterization of intergranular precipitates on grain boundaries by combination of FIB lift out method and TEM analyses: A case study in austenitic stainless steel.

A new characterization method is proposed to study intergranular precipitates of polycrystalline material in the planar manner. A dual beam focused ion beam (FIB) - scanning electron microscopy (SEM) was applied to fabricate thin FIB lamella with a grain boundary parallel to the lamella to investigate for transmission electron microscopy (TEM). Distributions, microstructures and compositions of intergranular precipitates of austenitic stainless steel were then examined by TEM, scanning transmission electron microscopy (STEM), and energy dispersive X-ray spectroscopy (EDS).

Structural and compositional study of precipitates in under-aged Cu-added Al-Mg-Si alloy.

Atomic scale characterization of fine precipitates in an under-aged Cu added Al-Mg-Si alloy was carried out by combination of atomically-resolved annular dark-field scanning transmission electron microscopy and energy dispersive X-ray spectroscopy. Two types of precipitates were observed in the alloy. In the case of ordered β" precipitates, β" was proposed as MgAlSi (x ≈ 1) with solute Cu atoms replacing Al site of β" precipitate.

Three-dimensional studies of intergranular carbides in austenitic stainless steel.

A large number of morphological studies of intergranular carbides in steels have always been carried out in two dimensions without considering their dispersion manners. In this article, focused ion beam serial-sectioning tomography was carried out to study the correlation among the grain boundary characteristics, the morphologies and the dispersions of intergranular carbides in 347 austenitic stainless steel. More than hundred intergranular carbides were characterized in three dimensions and finally classified into three different types, two types of carbides probably semi-coherent to one of the neighboring grains with plate-type morphology, and one type of carbides incoherent to both grains with rod-type morphology.

Microstructural characterization of GdBa2Cu3O7-δ superconductor films with BaHfO3 artificial pinning centers by scanning transmission electron microscopy.

Critical current (IC) of superconductor films under magnetic field is strongly influenced by dispersions and morphologies of artificial pinning centers (APCs) in general [1]. BaHfO3 (BHO) is acknowledged as the best candidates of APCs for REBCO films, which shows utmost thickness dependence and isotropic angular dependence of IC values for REBCO films [2]. Moreover, several researchers have focused on the nanostrains caused by the lattice mismatch at the interface between APCs and REBCO matrix, which are also the source for enhanced vortex pinning of the REBCO films [3].

Influences of calcination temperature on growth and superconducting properties of GdBa₂Cu₃O₇-δ films fabricated by fluorine-free metal organic deposition method.

GdBa2Cu3O7-δ is one of the best candidates for the superconducting coated conductors because it has high critical temperature and high critical current density under high magnetic fields. In this study, superconducting GdBa2Cu3O7-δ films were fabricated by fluorine-free metal organic deposition method via two different calcination temperatures, 723K and 873K, to examine the influence of calcination temperature on film growth and superconducting characteristics. Critical temperatures and critical current densities of the sample calcined at 873K were superior to the sample calcined at 723K.