Transmission Electron Microscopy Investigations Research Articles

Low Energy Twist Defects in Pentatwinned Silver Nanowires

Transmission electron microscopy investigation of networks of pentatwinned silver nanowires has identified the presence of nanoscale defects within individual wires, showing narrow regions of banded contrast normal to the nanowire axis (bamboo faults). Structural analysis using machine learning decomposition of scanning precession electron diffraction data identifies these bamboo faults as a pair of twist boundaries normal to the wire axis creating low energy coincident site lattices between the faulted region and the parent nanowire. This leads to a conservation of the relative misorientation of the twinned structure within the faulted region, leading to an apparent local rotation of the nanowire. Their presence after spraying and nonthermal processing suggests that they may form during nanowire synthesis. However, examination of the networks before and after cyclic straining finds an increase in the density of the defects, indicating that they may also form as a result of mechanical deformation.

New strategy to improve the overall performance of single-crystal superalloys by designing a bimodal γ′ precipitation microstructure

Advanced single-crystal superalloys, developed to improve the high temperature capability of gas turbines, often underperform in low-temperature conditions. This limitation compromises the overall reliability of turbine blades under complex service environments. This study introduces a novel strategy to enhance the overall performance of a fourth-generation single-crystal superalloy. Rapid liquid-nitrogen quenching following the aging treatment promotes extensive nucleation of ultrafine γ′ particles (γ′γ) with an average size of ∼10 nm, precipitated under extremely low supersaturation, as evidenced by high-resolution transmission electron microscopy (HRTEM) and atom probe tomography investigations. The combination of differential scanning calorimetry analysis, density functional theory calculations, and kinetic models verifies the high stability of γ′γ particles at low-temperature conditions around 900 °C. HRTEM observations reveal Orowan bypassing and dislocation cutting of γ′γ particles, leading to additional precipitation hardening by limiting dislocation motion in the γ phase and shear of primary precipitates. Consequently, a bimodal precipitation microstructure comprising γ′γ particles and primary γ′ phase significantly reduces the strain rate of low-temperature creep and nearly doubles the creep rupture life at 800 °C/735 MPa. Simultaneously, high-temperature properties at 900 °C/392 MPa and 1100 °C/137 MPa remain comparable to those of the original microstructure as the primary γ/γ′ microstructure is minimally affected by rapid cooling. This advancement improves overall performance and redefines the importance of small precipitates, broadening microstructure design concepts for future superalloy development.

In-situ Transmission Electron Microscopy for Sodium-ion Batteries.

Sodium-ion batteries have attracted tremendous attentions in recent years due to the abundance and wide distribution of Na resource on the earth. However, SIBs still face the critical issues of low energy density and unsatisfactory cyclic stability at present. The enhancement of electrochemical performance of SIBs depends on comprehensive and precise understandings on the underlying sodium storage mechanism. Although extensive transmission electron microscopy investigations have been performed to reveal the sodium storage property and mechanism of SIBs, a dedicated review on the in-situ TEM investigations of SIBs has not been reported. In this review, recent progress in the in-situ TEM investigations on the morphological, structural and chemical evolutions of cathode materials, anode materials and solid-electrolyte interface during the sodium storage of SIBs have been comprehensively summarized. The detailed relationship between structure/composition of electrode materials and electrochemical performance of SIBs have been clarified. This review aims to provide insights into the effective selection and rational design of advanced electrode materials for high-performance SIBs. This article is protected by copyright. All rights reserved.

High Resolution Scanning Transmission Electron Microscopy (S/TEM) Investigation Of Common Defects In Scandium and Aluminum Alloyed β-Ga2O3.

High Resolution Scanning Transmission Electron Microscopy (S/TEM) Investigation Of Common Defects In Scandium and Aluminum Alloyed β-Ga2O3.

The effect of Si content on microstructure and mechanical properties of Ti–Al–Ta–Si–N coatings

The evolution of the microstructure and mechanical properties of magnetron-sputtered Ti 1-x-y-zAlxTaySizN coatings with increasing the Si content from z = 0 to 0.3 is studied. Based on the results of the X-ray photoelectron spectroscopy and X-ray diffraction investigations, it is shown that the nanocomposite structure consisting of Ti–Al–Ta–Si–N crystallites and the Si3N4 amorphous tissue phase is formed in the coatings at z = 0.1. The evolution of the coating microstructure with increasing the Si content from the pronounced columnar morphology to the featureless nanocomposite morphology is demonstrated using scanning electron microscopy and transmission electron microscopy. The formation of the amorphous tissue phase in the coatings with z ≥ 0.12 is clearly shown by high-resolution transmission electron microscopy investigations. Variations of the mechanical properties of the coatings with the Si content are studied by nanoindentation. The Ti0.36Al0.44Ta0.10Si0.10N coating is found to have a maximum hardness of 41 GPa coupled with the highest H/E* and H3/E*2 ratios.

A quantum logic gate for free electrons

The topological charge m of vortex electrons spans an infinite-dimensional Hilbert space. Selecting a two-dimensional subspace spanned by m=±1, a beam electron in a transmission electron microscope (TEM) can be considered as a quantum bit (qubit) freely propagating in the column. A combination of electron optical quadrupole lenses can serve as a universal device to manipulate such qubits at the experimenter's discretion. We set up a TEM probe forming lens system as a quantum gate and demonstrate its action numerically and experimentally. High-end TEMs with aberration correctors are a promising platform for such experiments, opening the way to study quantum logic gates in the electron microscope.

Synthesis and spectroscopic investigations of Au(III) seleno-organic complexes

ABSTRACT. Heterocyclic pyridazine continues to attract great interest, mainly arising from a large variety of interesting pharmacological activities, herbicides, insecticides, and fungicides. On the other hand, the current interest in selenium-containing heterocycles is a result of their chemical properties and biological activities. In addition to the many recent publications dealing with the pharmacological potential of a selenium compound, new active formulations are an attractive target for chemical research. 2-((3-cyano-4,6-dimethylpyridin-2-yl)selanyl) acetic acid (pyd-Se), 2-((4-cyano-5,6-diphenylpyridazin-3-yl)selanyl)acetic acid (pydz-Se) and 2-((4,6-dimethyl quinolin-2-yl)selanyl)acetic acid (quin-Se) reacts with gold(III) chloride to produce metal ion complexes of specific composition. These synthesized complexes were characterized by elemental analyses, molar conductivity, FTIR, 1H NMR and transmission electron microscopy (TEM) investigations. The complexes were found to have the formulas [Au(pyd-Se)2]Cl, [Au(pydz-Se)2]Cl and Au(quin-Se)2]Cl, respectively.
 
 KEY WORDS: Au(III), Organoselenium, Complexation, FTIR, 1H NMR, TEM
 Bull. Chem. Soc. Ethiop. 2023, 37(5), 1141-1150. 
 DOI: https://dx.doi.org/10.4314/bcse.v37i5.7

In-Grain Ferroelectric Switching in Sub-5 nm Thin Al0.74 Sc0.26 NFilms at 1 V.

Analog switching in ferroelectric devices promises neuromorphic computing with the highest energy efficiency if limited device scalability can be overcome. To contribute to a solution, one reports on the ferroelectric switching characteristics of sub-5 nm thin Al0.74 Sc0.26 Nfilms grown on Pt/Ti/SiO2 /Siand epitaxial Pt/GaN/sapphiretemplates by sputter-deposition. In this context, the study focuses on the following major achievements compared to previously available wurtzite-type ferroelectrics: 1) Record low switching voltages down to 1V are achieved, which is in a range that can be supplied by standard on-chip voltage sources. 2) Compared to the previously investigated deposition of ultrathin Al1-x Scx Nfilms on epitaxial templates, a significantly larger coercive field (Ec ) to breakdown field ratio is observed for Al0.74 Sc0.26 Nfilms grown on silicon substrates, the technologically most relevant substrate-type. 3) The formation of true ferroelectric domains in wurtzite-type materials is for the first time demonstrated on the atomic scale by scanning transmission electron microscopy (STEM) investigations of a sub-5 nm thin partially switched film. The direct observation of inversion domain boundaries (IDB) within single nm-sized grains supports the theory of a gradual domain-wall driven switching process in wurtzite-type ferroelectrics. Ultimately, this should enable the analog switching necessary for mimicking neuromorphic concepts also in highly scaleddevices.

Ab initio supported study on the selective adsorption-induced microstructural difference of (Ti,Al)N/TiN and (Ti,Al)N/ZrN multilayers

Interface structure is essential for the mechanical properties of multilayers. Here, the effect of deposition process on the interface structure of arc-evaporated (Ti,Al)N/TiN and (Ti,Al)N/ZrN multilayers is studied by a combination of ab initio calculations and experiments. Based on x-ray diffractions and transmission electron microscope investigations, both multilayers with close modulation ratio and period reveal face centered cubic (fcc) structure with coherent interfaces. Nevertheless, thin (Ti,Zr)N layers are formed near the interfaces in (Ti,Al)N/ZrN multilayer, but are absent in (Ti,Al)N/TiN multilayer. Ab initio calculations suggest the selective absorption of Ti and Zr adatoms onto the surface of (Ti,Al)N/ZrN multilayer during deposition, which leads to the formation of (Ti,Zr)N-rich layers by interface. However, (Ti,Al)N/TiN multilayer is predicted to have almost constant surface adsorption of different adatoms.

Creep-induced redistribution of alloying elements in CZ1 zirconium alloys

Introducing minor alloying elements is an effective strategy to improve the corrosion and mechanical properties of zirconium alloys for nuclear applications. During in-reactor service, external environment and stress can affect the distribution of alloying elements, substantially changing the degradation process of zirconium alloys. To date, there is a lack of in-depth understanding of the interaction between creep and microchemistry changes. Here, we conducted systematic transmission electron microscopy (TEM) and atom probe tomography (APT) investigations to address creep-induced redistribution of alloying elements in CZ1 (Zr-Sn-Nb-Fe-Cr-Cu) zirconium alloy with different initial microstructures. Nb, Fe, Sn, and Cu are found to co-segregate at grain boundaries. The higher the intermediate annealing temperature, the larger the Gibbsian interfacial excesses of solute elements are. We further demonstrate that creep can reduce the excess value of Fe at grain boundaries due to the coarsening of Zr-Fe-Cr second phase particles via grain boundary and dislocation pipe diffusion. At the same time, the excess value of Sn is increased by diffusing from the matrix to grain boundaries. Moreover, Cu as a minor element in the concentration range of 0.05–0.3 wt.% is found to segregate at dislocations to form the Cottrell atmosphere and develop Cu-rich nanoclusters for suppressing dislocation motion. The new understanding of the segregation and clustering of minor alloying elements provides guidance for developing zirconium alloys with enhanced creep resistance.

Exsolution of oxygen impurity from diamond lattice and formation of pressurized CO2-I precipitates

Diamond single crystals showing Infra-red features of pressurized CO2-I phase were studied using Transmission Electron Microscopy (TEM) and tomography. Numerous O-containing precipitates with sizes up to 45 nm are observed. The absolute majority of these precipitates decorate dislocation loops or are located inside them; individual scattered precipitates are also present. Morphology of the precipitates varies from quasi-isometric octahedra to highly flattened elongated ones. Close association of the precipitates with the dislocation loops implies their formation by exsolution of oxygen impurity from diamond lattice; the size distribution of the precipitates suggests that the equilibrium state is not yet reached. Presumably, the morphology and precise chemical composition depend on P-T-t evolution of the diamond crystal and corresponding changes in oxygen supersaturation in the lattice. The CO2-containing diamonds often contain micron-sized hexagonal lamellar inclusions. TEM investigation of a lamellae reveals that it consists of high quality graphite showing partial epitaxial relation with comprising diamond. The gap between the graphite and diamond may be enriched with oxygen impurity.

Reverse Engineering Analysis of Optical Properties of (Ti,Cu)Ox Gradient Thin Film Coating

Analysis of the optical properties of a gradient (Ti,Cu)Ox thin film is presented in this paper. The thin film was prepared using reactive co-sputtering of Ti and Cu targets. The desired elemental concentration profiles of Cu and Ti versus the thin film thickness were obtained by changing the power delivered to the magnetron equipped with Cu, while the powering of the magnetron equipped with the Ti target was maintained at a constant level during the film deposition. Optical properties were analysed using the reverse engineering method, based on simultaneously measured optical transmittance and reflectance. Detailed microstructure analysis performed using transmission electron microscopy investigations revealed that the thin film consisted of at least four areas with different structural properties. Finding a satisfying fit of theoretical to experimental data required taking into account the heterogeneity in the material composition and microstructure in relation to the depth in the prepared gradient thin film. On the basis of the built equivalent layer stack model, the composition profile and porosity at the cross-section of the prepared gradient film were evaluated, which agreed well with the obtained elemental and microscopy studies.

Green Synthesis of Au-doped SnO 2 Nanoparticles Using Teucrium Polium Plant Extract for the Evaluation of Their Physicochemical and Antibacterial Properties

Background & Objective: The biological production of nanoparticles (NPs) is a technique that has garnered a lot of interest because it is inexpensive, straightforward, and friendly to the natural environment. This study explores the green synthesis of Au-doped SnO 2 NPs using Teucrium polium plant extract and evaluates their antimicrobial properties in comparison with two commonly used antibiotics.
 Materials & Methods: Initially, an extract of Teucrium polium was made using water, and then it was combined with solutions of tin (II) chloride dehydrate [SnCl 2 .2H 2 O] and gold (III) chloride trihydrate [HAuCl 4 .3H 2 O]. The crystal structure was studied using X-ray diffraction (XRD). The form, structure, and grain size of the NPs were analyzed using scanning electron microscope (SEM) and transmission electron microscope (TEM). The synthesized NPs were tested for their antibacterial properties.
 Results: The XRD and EDS analyses revealed that the SnO 2 : Au phase formed an average crystallite size of 22 nm and an Au dopant content of around 2%. The SEM and TEM investigations demonstrated that the NPs were formed in a regular and nanoscale manner, with diameters ranging from 25 to 30 nm. MIC and MBC of SnO 2 : Au NPs against the studied bacteria (S.aureus ATCC 43300, P.aeruginosa PAO1) were reported 9.6±0.13- 9.6±0.07 μg/mL and 25.9±11.5- 32.5±11.2 μg/mL.
 Conclusion: Green-synthesized NPs exhibit significant antimicrobial activity against both Gram-positive and Gram-negative bacteria, even at low concentrations. The NPs effectively eliminate bacteria and prevent biofilm formation.

Optimal Concentration and Duration of Endotracheal Tube Coating to Achieve Optimal Antimicrobial Efficacy and Safety Balance: An In Vitro Study

Ventilator-associated pneumonia (VAP) is a common and genuine complication in fundamentally sick patients accepting mechanical ventilation. Silver nitrate sol-gel (SN) has been proposed as a potential preventative measure against VAP. Be that as it may, the arrangement of SN with distinctive concentrations and pH values remains a basic factor influencing its effectiveness. Silver nitrate sol-gel was arranged with distinctive concentrations (0.1852%, 0.03496%, 0.1852%, and 0.01968%) and pH values (8.5, 7.0, 8.0, and 5.0) separately. The antimicrobial action of the silver nitrate and NaOH arrangements were assessed against Escherichia coli as a reference strain. The thickness and pH of the arrangements were measured, and biocompatibility tests were performed on the coating tube. The auxiliary changes in the endotracheal tube (ETT) tests after treatment were analyzed utilizing electron microscopy (SEM) and transmission electron microscopy (TEM). The pH estimations of the diverse arrangements showed that the pH values shifted depending on the test conditions, with pH values extending from 5.0 to 8.5. The consistency estimations of the arrangements showed that the thickness values expanded as the pH values drew closer to 7.5 and diminished when the pH values went over 7.5. The antimicrobial action of the silver nitrate and NaOH arrangements were successful against Escherichia coli, with microbial checks decreasing in concentration (0.03496%, 0.1852% (pH: 8), and 0.01968%). The biocompatibility tests revealed tall cell reasonability rates, demonstrating that the coating tube was secure for therapeutic utilization and did not hurt typical cells. The SEM and TEM investigation gave visual proof of the antibacterial impacts of the silver nitrate and NaOH arrangements on the bacterial surface or interior of the bacterial cells. Moreover, the investigation revealed that a concentration of 0.03496% was the foremost successful in hindering the development of ETT bacterial colonization at the nanoscale level. We propose that cautious control and alteration of the pH and thickness of the arrangements are essential to guaranteeing the reproducibility and quality of the sol-gel materials. The silver nitrate and NaOH arrangements may serve as a potential preventative degree against VAP in sick patients, with a concentration of 0.03496% appearing to show the most elevated viability. The coating tube may serve as a secure and viable preventative measure against VAP in sick patients. Further investigation is required to optimize the concentration and introduction time of the arrangements to maximize their adequacy in avoiding VAP in real-world clinical settings.

Molten salt synthesis and formation mechanism of Ti3AlC2: A new path from Ti2AlC to Ti3AlC2

AbstractFine, pure Ti3AlC2 powder is prepared in a very mild condition via Ti3Al alloy and carbon black with the assistance of molten salts. X‐ray diffraction, scanning electron microscopy, TG‐DSC, and transmission electron microscopy (TEM) characterizations show that the high purity, nanosized Ti3AlC2 can be obtained at 900°C with the 1:1 salt‐to‐material ratio. The formation mechanism of Ti3AlC2 through this strategy of alloy raw material is fully studied under further TEM investigations, showing that the reaction process can basically be described as Ti3Al and C → TiAl and TiC → Ti2AlC and TiC → ψ and TiC → Ti5Al2C3 and TiC → Ti3AlC2, where the key ψ, a modulated Ti2AlC structure, is determined for the first time containing alternate‐displacement Al layers along (0 0 0 2) of Ti2AlC phase with a distinct selected area electron diffraction pattern. Such alternant displacement is considered a precondition of forming Ti5Al2C3 through topotactic transition, followed by Ti5Al2C3 converting into Ti3AlC2 by the diffusion of Ti, C atoms in the outside TiC. Several parallel orientations can be observed through the phase transition process: Ti2AlC (0 0 0 2)//ψ (0 0 0 1), ψ (0 0 0 1)//Ti5Al2C3 (0 0 0 3), Ti5Al2C3 (0 0 0 3)//Ti3AlC2 (0 0 0 2). Such parallel orientations among these phases apply an ideal condition for the topotactic reaction. The distinct path of the phase transition brings a significant change of heat effect compared with the traditional method, leading to a fast reaction rate and a mild reaction condition.

Irradiation-enhanced Interactions at UO2/Al2O3/Al Interfaces

Combustion synthesis is used to prepare thin UO2 films on aluminum alloy substrates. This simple preparation method involves electrospraying uranyl nitrate + acetylacetone + 2-methoxyethanol solution on the substrate, followed by a short annealing at 350 or 550 °C. The irradiation of films with a 40Ar2+ ion beam (energy of 1.7 MeV and fluences of 7.7 × 1016 and 1.3 × 1017 ions/cm2) is conducted to investigate irradiation-induced restructuring processes. High-resolution transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) investigations show that the annealing temperature significantly influences the crystallinity and stability of materials during irradiation. A small amount of Mg in the alloy substrate diffuses into the amorphous Al2O3 interfacial layer between the film and the substrate. Local thermal spikes from the incoming ions facilitate the irradiation-induced mixing of immiscible Al2O3 and UO2 for the materials prepared at 350 °C. This mass diffusion produces relatively large cavities at the interface. Selective diffusion of a more significant amount of Mg for the materials prepared at 550 °C suppresses the mixing of the Al2O3 interlayer with the film but forms MgyU1–yO2±x solid solutions during irradiation. Local thermal heating triggers the precipitation of a discontinuous crystalline MgO layer close to the film surface. The enhanced and selective diffusion of Mg into the film makes the materials prepared at 550 °C more robust and mechanically stable than those prepared at 350 °C.

Hot-rolled Al-added medium Mn steel (Fe-8Mn-2.85Al-1Si-0.2C): Microstructural evolution and tensile behavior

In this study, a low Al (<3%) added medium manganese steel has been developed through melting casting route in an open-air induction furnace. The cast steel ingot has been intercritical annealed at 720 °C after hot deformation, that includes hot forging and hot rolling treatment, respectively. Microstructure characterization coupled with X-ray diffraction (XRD) has been performed after each processing step to understand the extent of austenite formation and its subsequent transformation to ferrite/martensite. The processed steel possesses the ultimate tensile strength, yield strength and ductility of 1000±20 MPa,700±10 MPa and 18.5 ± 0.5, respectively. To understand the possible cause of enhanced strength and deformation mode rietveld analysis has been carried out. It reveals that developed (final processed) steel possesses ∼18% (volume%) of austenite that subsequently reduced to ∼6.139% after tensile testing, indicating significant transformation of austenite to martensite (continuous and enhanced TRIP effect). The morphological characteristic of martensite in developed steel has been investigated using transmission electron microscopy (TEM). It reveals lath morphology of martensite due to low carbon content. The TEM and 3D atom probe analysis reveals the precipitation of intergranular type kappa (k) carbide in intercritically annealed specimens due to probable segregation of C and Al. However, volume fraction of the same is low. The SFE of the steel has been found to be ∼16 mJ m− 2, calculated by the modified Olson and Cohen method that also concludes TRIP is the preferred deformation mechanism in the developed steel.

Quercetin-loaded Liposomes Effectively Induced Apoptosis and Decreased the Epidermal Growth Factor Receptor Expression in Colorectal Cancer Cells: An In Vitro Study.

Quercetin is a flavonoid having anti-cancer properties; however, it has low stability, insufficient bioavailability, and poor solubility. This study aimed to load quercetin on nanoliposomes to enhance its efficiency against SW48 colorectal cancer cells. The cytotoxicity of free-quercetin and quercetin-loaded nanoliposomes on the expression of the epidermal growth factor receptor (EGER) gene was investigated. This present in vitro study was conducted at Yasuj University of Medical Sciences (Yasuj, Iran) in 2021. In this in vitro study, the lipid thin-film hydration method was used to synthesize quercetin-loaded liposomes. Additionally, high-performance liquid chromatography (HPLC) analyses, dynamic light scattering (DLS), and transmission electron microscopy (TEM) investigations were used to characterize nanomaterials. Following that, MTT, flow cytometry, and real-time PCR were used to investigate the cytotoxicity of quercetin-loaded liposomes on the colorectal cancer cells SW48 cell line, the incidence of apoptosis, and the expression of the EGFR gene in these cells. Statistical analysis was performed using the SPSS (version 26.0), and the graphs were created with the GraphPad Prism version 8.4.3. P<0.05 was considered statistically significant. The nanoparticles were spherical, homogenous, and 150±10 nm in size. According to HPLC, Quercetin had a 98% loading capacity. Although both free quercetin and quercetin-loaded liposomes indicated significant cytotoxicity against cancer cells (P˂0.001), the combined form was significantly more active (P=0.008). 50 µg/mL of this compound reduced the viability of SW48 cells by more than 80% (IC50 10.65 µg/mL), while the viability of cells treated with free quercetin was only 66% (IC50 18.74 µg/mL). The apoptosis was nearly doubled in the cells treated with quercetin-loaded nanoliposomes compared to free quercetin (54.8% versus 27.6%). EGFR gene expression, on the other hand, was significantly lower in cells treated with quercetin-loaded liposomes than the quercetin alone (P=0.006). When combined with nanoliposomes, quercetin had greater anti-proliferative, apoptotic, and anti-EGFR expression than free quercetin.

Formation of nanocrystalline AZ31B Mg alloys via cryogenic rotary swaging

A bulk nanocrystalline AZ31B Mg alloy with extraordinarily high strength was prepared via cryogenic rotary swaging in this study. The obtained alloy shows finer grains, higher strength, and a negligible tension-compression yield asymmetry, compared with that prepared via room-temperature rotary swaging. Transmission electron microscopy investigations showed that at the initial stage, multiple twins, mostly tension twins, were activated and intersected with each other, thereby refining the coarse grains into a fine lamellar structure. Then, two types of nanoscale subgrains were generated with increasing swaging strain. The first type of nanoscale subgrain contained twin boundaries and low-angle grain boundaries. This type of subgrain appeared at the twin-twin intersections and was mainly driven by high local stress. The second type of nanoscale subgrain was formed within the twin lamellae. The boundaries of this type of subgrain did not contain twin boundaries and were transformed from massive dislocation arrays. Finally, randomly oriented nanograins were obtained via dynamic recrystallization, under the combined function of deformation heat and increased stored energy. Compared with room-temperature rotary swaging, cryogenic rotary swaging exhibits a slower grain refinement process but a remarkably enhanced grain refinement effect after the same five-pass swaging.

Influence of thermo-mechanical treatment in austenitic and ferritic field condition on microstructural and mechanical properties of reduced activation ferritic-martensitic steel

Abstract 9Cr-1W-0.06Ta reduced activation ferritic-martensitic (RAFM) steel has been investigated in normalized and tempered (N + T) condition and in thermo-mechanically treated (TMT) in austenitic and ferritic field conditions. RAFM steel in N + T condition has a tempered martensitic structure (body-centred tetragonal, bct). It is unstable and will transfer into a stable body-centered cubic (bcc) in the structure during a long period subjected to high temperatures. To make it stable structure, the steel was subjected to austenitization at 1423 K for 10 min, and then cooled in still air (≈−1 K s−1) to 973 K and this temperature was maintained for 2 h in furnace to fully convert austenite into ferritic phase then the steel was subjected to 25% reduction in thickness by hot rolling. Optical, scanning and transmission electron microscopic investigations have been carried out to assess the microstructural changes of the steel N + T and TMT conditions. Hardness, tensile and creep studies are carried out and the results were correlated with the microstructural studies. TMT processed steel resulted in coarser prior austenite grains and exhibited ferrite in phase with fine distribution of M 23C6 and MX precipitates whereas N + T condition is subjected to tempered martensitic structure with coarser M 23C6 and MX precipitates. Even though ferrite phase present in TMT processed steel it exhibits higher tensile and creep strengths due to the presence of high dislocations and finer distribution of precipitates than the N + T condition.