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The microstructural evolution of Al–2.24 Cu–1.42 Mg–0.9 Fe–0.9 Ni (AA2618) alloy after 195 °C/18 h aging, as well as after 180 and 240 °C/100 h creep, has been studied by transmission electron microscopy and high resolution electron microscopy (HREM). The Guinier–Preston–Bagaryatsky (GPB) zones/co-clusters, S″, S, and Al9FeNi phases co-exist in the alloys after the 195 °C/18 h aging. After creep, precipitates become coarser and the transformation of GPB zones/co-clusters and S″ to S phase take place. A large number of GPB zones/co-clusters as those in aging state exist after 180 °C/100 h creep which possibly dynamically precipitates during the creep process. After the 240 °C/100 h creep, most of the precipitates are S variants with a few GPB zones and S″ phase. More dislocations appear upon which precipitate colonies form after creep. HREM images show that most of the early precipitates less than about 5 nm cannot exhibit perfect lattice image for the existence of stress. However, certain GPB/co-clusters possessing coherent relationship with the matrix can also be observed. HREM demonstrates that certain S particles viewed along [100]S and [013]S have classic orientation relationship with the matrix, and that those upon the dislocations depart from the standard orientation.

The effects of copper addition on the machinability and corrosion resistance of martensitic stainless steel 4Cr16Mo are presented in the article. The results showed that the machinability of stainless steel 4Cr16Mo was obviously improved by adding Cu. When the content of copper in the stainless steel was 1.4%, the machinability of stainless steel was optimal. With the increase in the content of copper, the corrosion resistance of stainless steel 4Cr16Mo was improved. From the observation of the electron backscattered diffraction (EBSD) and high resolution electron microscopy (HREM), it can be seen that Cu-rich phases were dispersed in the stainless steel, and determined to be about 10 nm.

The structures of martensites in a Cu–11.2 wt% Al–3 wt% Ni specimen, which was quenched from 1173 K, have been studied by high resolution electron microscopy (HREM) and diffraction techniques. Two kinds of martensites, i.e. β′1 and γ′1, coexisting adjacent to each other in the specimen were observed. The γ′1 matensite consists of microtwins with monoclinic structure. Three variants of the twin structure, i.e. {1 2 1}, {2 1 0} and {1 0 1} twins, are arranged within a single plate. The β′1 martensite possesses basically ordered N9R structure, but mixed with thin 2H domains. Some diffraction spots of this martensite shift along the [0 0 1] direction. In addition, extra weak reflections appear in the diffraction pattern due to heterogeneous atomic displacements. The microstructural features of the martensites are examined and discussed.

High-resolution transmission electron microscopy observations on rapidly solidified Nd-Fe-B alloys are presented. The results show the existence of nanophases of different compositions to the nominal Nd2Fe14B as-prepared alloy, which was detected prior to the fast-quenching process. In particular, iron-enriched nanophases are commonly found among the wide variety of nanophases in the final alloy. The possible mechanisms, as well as their relevance to the understanding of the properties of these magnetic materials, are also discussed.

The fine structure of unhydrated cement clinker Ca4Al6SO16 (C4A3S) and its four superstructures have been studied by means of electron diffraction and high resolution electron microscopy (HREM). The match between experimental images and simulated ones verifies the result of X-ray structural analysis: C4A3S having a cubic lattice with space group l43m,Z = 2. The frequent apperance of forbidden reflections such as 1/2, −1/2, 0 along the 〈110〉* directions of C4A3S imply the presence of superstructures which may be due to an orderly inverse occupation of Ca2+ ions. Various structure models based upon the observed structural images have been proposed for these four superstructures. A new cubic phase witha′ = 1.5 nm is also found by selected area electron diffraction (SAED).

Although facilities for high resolution electron microscopy (HREM) are available, interpretation of micrographs at high magnifications is far from unambiguous. The interpretation of the micrographs using a computed structure analysis program is therefore necessary. The paper presents the theory behind HREM, together with a computer method for image interpretation. Special reference is made to the JEOL JEM 200CX transmission electron microscope used in the study of sodium beta-alumina.

Two kinds of bulk mesophases separated by quinoline from Polyvinylchloride (PVC) pitch and from 3, 5-xylenol-formaldehyde resin (XF) pitch were studied by high resolution electron microscopy. The ease of graphitization of both bulk mesophases has been examined by heat-treating them up to 1080 and 2600° C. PVC bulk mesophase mostly shows preferred long range orientation (aromatic carbon layers roughly parallel to each other), but also contains minor components where the molecular orientation occurs only over small distances, or not at all. When heat-treated at high temperature PVC bulk mesophase changes mainly into highly graphitized lamellar crystals. Similarly treated XF bulk mesophase does not show any preferred orientation and leads to porous nongraphitizable material.

Crystals of poly (p-phenylene sulphide) were obtained from anα-chloronaphthalene solution. The chain axis (the crystalc-axis) was usually normal to the support-film. For these crystals, high-resolution electron microscopic images were taken as the projection of the molecular chains on theab plane along the chain axis. Occasionally it was observed that crystals took different orientations on the support-film for undefined reasons. From such orientations, the high-resolution image of a crystal rotated by 28.7° around thea-axis from the usual orientation, was also obtained.