Microstructural Characterization Research Articles

The Improved Age Hardening Response of Mg-11Al Alloys with Ag, Sc Addition and Corresponding Microstructure Characterization

The Improved Age Hardening Response of Mg-11Al Alloys with Ag, Sc Addition and Corresponding Microstructure Characterization

The effect of artificial metakaolin coarse aggregate on the mechanical and durability properties of lightweight geopolymer concrete

<p style="text-align:justify; margin-bottom:11px"><span style="font-size:11pt"><span style="line-height:150%"><span style="font-family:Calibri,"sans-serif""><span lang="PT-BR" style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:"Times New Roman","serif""><span style="color:#131413">This study presents a unique methodology for investigating the properties of  Metakaolin Coarse Aggregates (MCA). The NaOH ratios were varied as 8M, 10M, 12M, and 14M, while the NaOH to Na<sub>2</sub>SiO<sub>3</sub> ratio was maintained at 0.5 entire study. The liquid-to-binder (L/B) ratios set at 0.3, 0.35, and 0.4. Testing was conducted on the MCA to determine its physical and mechanical properties, comparing them with those of Natural Coarse Aggregate (NCA). Notably, the 8M mix with a 0.4 L/B ratio was found to be economical for producing MCA and was selected for further research. This chosen mix was then employed to prepare geopolymer concrete with 50% MK and 50% PA, with L/B ratios set at 0.4, 0.45, and 0.5. The NaOH ratio and Na<sub>2</sub>SiO<sub>3</sub> to NaOH ratio were maintained at a constant 8M and 2, respectively. Mechanical and durability properties were compared between Geopolymer concrete with NCA and Geopolymer concrete with MCA. The test results demonstrate that MCA in geopolymer concrete can effectively replace NCA in geopolymer concrete, making it a viable option for structural members. Additionally, microstructural characterization was performed on Geopolymer concrete with MCA mixes with varying L/B ratios of 0.4, 0.45, and 0.5, at 28 days. The study specifically focuses on the Interfacial Transition Zone (ITZ) between MCA and geopolymer paste, revealing an improvement in ITZ and microstructure in the GMCA sample with a 0.4 L/B ratio compared to other mixes.</span></span></span></span></span></span></span></p>

Characterization of Microstructure of Fe-TiC and Fe-B4C Composites Using Ultrasonic Measurements

In this paper, an iron (Fe) matrix reinforced with boron carbide (B4C) and titanium carbide (TiC) was produced by conventional furnace sintering at the same compositions and temperatures. Experimental data on the change in ultrasonic velocity parameter, densities and porosity of these two different microstructure composites during microstructure development are reported. The microstructural phases were characterized by metallographic studies and hardness measurements. The velocities of ultrasonic longitudinal waves were measured by the pulse- echo method using the transmit/receive probe. In the Fe-TiC composite sample, ultrasound longitudinal wave velocity, hardness and porosity increased linearly depending on the increasing amount of TiC. In the Fe-B4C composite sample, on the other hand, there is a linear increase in general depending on the increasing amount of B4C, and there is a sharp decrease in the amount of 8,33% B4C. The reason for this decrease and other results are explained by taking into account SEM and XRD analyzes.

Effect of Pressure on the Linear Friction Welding of a Tool Steel and a Low‐Alloy Carbon Steel

This study investigates the effect of pressure (burn‐off and forging) on the mechanical properties of the joint between a wear‐resistant tool steel and a low‐alloy steel using linear friction welding. The authors have previously demonstrated the feasibility of joining these dissimilar materials, but the impact of pressure on the mechanical properties of the bimaterial joint remains unclear. To address this, weld samples are prepared using different pressures and are characterized through microstructural analysis, microhardness, tensile testing, and fractography. The results show that the strength of the joint between the wear‐resistant tool steel and the low‐alloy carbon steel increases as the pressure increases up to a certain point, after which a decrease is observed. The highest joint strength is achieved at a pressure of 360 MPa. The microhardness profile measurement reveals a distinct transition zone at the interface between the two materials, with varying hardness values. The hardness of the low‐alloy carbon steel increases near the interface, while that of the wear‐resistant tool steel decreases. This transition zone is found to be narrower at higher pressures. Microstructural characterization shows that the grain structure near the interface differs from that of the starting base materials.

Mechanical Properties and Corrosion Behavior of SiC Reinforced High Entropy Alloy (Ni-Co-Fe-Ti) matrix Composites Produced by Microwave and Conventional sintering Techniques

Abstract The aim of this work is to synthesize SiC reinforced Ni-Co-Fe-Ti composite using powder metallurgy (PM) method. Two sintering methods, conventional sintering (CS) using a tubular furnace and microwave sintering (MWS), are employed to synthesize three different weight percentages of SiC (3 wt.%, 6 wt.%, and 9 wt.%) within a Ni-Co-Fe-Ti matrix. The densification behavior of synthesized Ni-Co-Fe-Ti-SiC composites are studied using sinterability function. The highest sinterability of 0.89 was achieved for Ni-Co-Fe-Ti-0 wt.wt.% SiC alloy. The densification rate was found to be higher in MW sintered composites compared to those sintered conventionally. 3.5 wt.% NaCl solution was considered for corrosion examination and it was determined that Ni-Co-Fe-Ti- 9 wt.% SiC MW sintered composite exhibit highest corrosion resistance. Ni-Co-Fe-Ti-9 wt.%SiC MW sintered composite exhibits higher compressive strength of 1050 MPa than conventional sintered Ni-Co-Fe-Ti-9 wt.%SiC (625MPa). Ni-Co-Fe-Ti-6wt.% SiC MW sintered composite possess highest hardness of 58 HRC among other prepared composites. Interestingly, decreasing trend in hardness was observed for further inclusion of SiC with Ni-Co-Ti-Fe matrix. Scanning electron microscopy (SEM) and microstructural characterization technique shows the formation of pores in the conventional sintered composites. But, there is no formation of pores in the MW sintered composite of all the composition. Tribological studies were conducted using pin on disc method. Worn surface morphology was analyzed and it shows that severe pullout was observed in the worn surface of conventional sintered Ni-Co-Fe-Ti- 6wt.%SiC.The best optimum set of parameters (Sliding Speed 1146 rpm, SiC inclusion 6 wt.%, Applied Load 20 N) were found out using Taguchi method.

Characterization of microstructure and wear behavior of nickel modified Zn-27% Al alloy casting

Characterization of microstructure and wear behavior of nickel modified Zn-27% Al alloy casting

Impact of T6 heat treatment on the microstructure and mechanical characterization of Al7075-graphene nanoplatelets- Beryl hybrid composites

Impact of T6 heat treatment on the microstructure and mechanical characterization of Al7075-graphene nanoplatelets- Beryl hybrid composites

Evolution of microstructure and tensile behavior in an interstitial strengthened high entropy alloy

The microstructural evolution and mechanical properties of Fe61.5Cr17.5Ni11.5Al8C1.5 high-entropy alloys (HEAs) were investigated to establish an optimal set of annealing conditions that would result in reasonable recrystallized fractions across the different temperatures and durations. The evolution of the microstructure was analyzed, tracking the transformation from the rolling texture to the recrystallization texture, as well as any phase transformations that occurred. The grain size distribution, overall microstructural features, and the effects of annealing temperature and time on the tensile properties of the HEAs were examined and discussed. The alloy was subjected to cold rolling and subsequent annealing treatments, revealing a single FCC phase after homogenization at 1260 °C. The cold-rolled samples retained the FCC structure at lower annealing temperatures (400 °C and 500 °C) but underwent a phase transformation to BCC at higher temperatures (600 °C to 900 °C). Microstructural characterization demonstrated that cold rolling introduced a high density of dislocations, while annealing facilitated recrystallization and grain growth. The tensile tests indicated that HEA samples exhibited a yield strength of 570 MPa and ductility of ∼36 % with large grain size after a long annealing at elevated temperature. In contrast, after being heat-treated at 1200 °C for 2 min, HEAs restrict FCC-to-BCC phase transformation and exhibit small grain size (3.2 µm) with M23C6-like carbide precipitation in the FCC matrix. Smaller grains provide additional boundaries, which restrict dislocations to bypass these boundaries. While carbide precipitates at grain boundaries and inside grains, it strengthens the material by pinning grain boundaries and restricting dislocation movement, resulting in a yield strength of 610 MPa and ductility of ∼41 %.

Fe-based metallic glass coatings with suppressed cracks and enhanced wear resistance prepared by extreme high-speed laser cladding

Fe-based metallic glass (MG) coatings draw great attentions due to their excellent wear resistance. The recently developed extreme high-speed laser cladding (EHLC) provides a promising method for their fabrication but limited by the strong tendency to crack. Besides that, the deep insight into the structure evolution and the failure mechanism of the coating is still lacked. Thus, the understanding of the crack origin and the prevention of crack are of great importance. In the present work, Fe-Mo-Cr-Y-C-B MG coatings with adjustable glassy phase content were successfully fabricated by EHLC. The microstructure characterization of the coatings reveals that the cracks is main caused by the hard and brittle nanocrystalline phases precipitations of monoclinic Mo12Fe22C10 and (Fe, Cr)23C6 carbides in the heat affected zone. Therefore, the cracking of the coatings can be effectively reduced by increasing the glassy phase content. Subsequently, the hardness distribution, wear performance and wear mechanism of the coatings were investigated. The results showed that increasing the glassy phase content can effectively achieve low wear rate. The prepared Fe-Mo-Cr-Y-C-B MG coatings exhibit abrasion loss as low as 3.54·10−6 mm3 (N m)−1, which is an order of magnitude lower than that of the 45# steel substrate. The wear of the coatings is primarily attributed to the fatigue wear accompanied with slighting oxidative wear. By suppressing the brittle precipitated crystalline phases in the coating, the fatigue wear can be reduced and the wear resistance of the coatings can be improved. The present work provides insights into the crack prevention and were performance improvement of the Fe-based MG coatings prepared by EHLC.

Construction of Lactobacillus casei-loaded Water-in-oil High Internal Phase Emulsion and its Study on Anti-breast Cancer Properties

Objective: To prepare an oil-in-water high internal phase emulsion containing Lactobacillus casei, and to optimize and characterize the preparation process. To explore the therapeutic effect of the probiotic-carrying emulsion on in situ breast cancer in mice. Methods: Using corn oil, sodium alginate, polyglycerin ricinoleate and L. casei as raw materials, the high internal phase emulsion containing probiotic oil-in-water was prepared by high-speed homogenization method. The optimal preparation process was obtained through single factor investigation, microstructure characterization, stability investigation and in vitro simulation digestion experiment. Ten female BALB/c mice (SPF grade, 18–20 g) were selected. After the in situ breast cancer model was successfully established, the mice were randomly divided into experimental group and control group, with 5 mice in each group. The mice were administrated with probiotic-loaded emulsion and normal saline respectively, and were administrated with the stomach every other day for 10 days. The change of tumor volume during treatment and tumor mass at the end of treatment were recorded. Results: The optimum process of emulsion was: With the concentration of 5% Polyglycerin ricinolate, 75% aqueous volume, 3000r/min homogenizing speed, 30 s homogenizing time and 2% aqueous sodium alginate concentration, a high internal phase emulsion with a particle size of 9.33 ± 1.74 μm and an appearance of milky paste was prepared. The inclusion rate of probiotics reached 90.97 ± 27.09%. Breast cancer anti-tumor experiment showed that the tumor inhibition rate of the experimental group reached 33.78% compared with the control group. Conclusion: Water-in-oil high internal phase emulsion can effectively protect L. casei and reduce the loss of live probiotic when probiotics pass through the digestive fluid environment. Oral intragastric high internal phase emulsion containing L. casei oil-in-water has a certain therapeutic effect on breast cancer.

Microstructure characterization and formability assessment of electron beam welded Nb-10Hf-1Ti (wt%) refractory alloy sheets

Formability study on welded blanks of Nb-based refractory alloy C-103 (Nb-10Hf-1Ti (wt%)) has tremendous potential for utilizing smaller sheets for realization of large-size divergent portions of upper-stage liquid engine nozzle of satellite launch vehicles and thrusters of attitude orbital control systems. In this work, vacuum-annealed monolithic C-103 sheets were electron beam welded successfully to obtain defect-free welds and detailed microstructural and mechanical characterizations were investigated. Columnar epitaxial grains were found in fusion zone (FZ) instead of equiaxed grains in base metal (BM). Detailed SEM and HRTEM analyses revealed spherical shape of nano-size HfO2 precipitates with monoclinic crystal structure in the C-103 sheet. Further, microhardness across the weld cross-section indicated that the FZ had a uniform and maximum hardness of ~195 HV0.5 due to formation of finer nano-sized HfO2 precipitates with higher number density, followed by a lowering of hardness in a narrow heat-affected zone. A marginal reduction in tensile strength of ~6 % with a considerable decrease in ductility of ~29 % was noticed for the welded sample. However, fracture occurred in the BM region, indicating good weld integrity. Furthermore, formability of the welded blanks was evaluated in terms of limiting dome height (LDH), forming limit diagram, and deep drawn cup depth. The effect of the presence of WZ on uniaxial, plane strain, and biaxial tensile strain paths on the formability of the C-103 sheet was estimated for the first time, and the results were compared with the monolithic sample. It was noted that the failure limit of the welded specimens decreased compared to that of the monolithic sample, resulting in a lower LDH of approximately 69 % and 62 % when deformed along plane strain and biaxial tensile strain paths, respectively. However, marginal variation in LDH was observed for the uniaxial strain path. Also, the welded blank had more resistance to material flow into the die cavity due to the harder weld region, resulting in a reduction of deep drawn cup depth by 52 % than that of the monolithic blank. The overall results concluded that the presence of the WZ significantly affected the formability of the C-103 sheet, especially in plane strain and biaxial strain paths. However, the fracture was never found to be propagating along the weld line, indicating the ability of the weld to sustain large plastic strains. This study provides insightful information on the formability of electron beam welded C-103 sheets for the successful fabrication of space components.

Improvement of Electrical and Thermal Properties of Carbon Nanotube Sheets by Adding Silver Nanowire and Mxene for an Electromagnetic-Interference-Shielding Property Study

Hybrid carbon nanotube (CNT) sheets were fabricated by mixing CNTs with silver nanowires (AgNWs) and MXene to study their electromagnetic-interference (EMI)-shielding properties. CNT/AgNW and CNT/MXene hybrid sheets were produced by ultrasonic homogenization and vacuum filtration, resulting in free-standing CNT sheets. Three different weight ratios of AgNW and MXene were added to the CNT dispersions to produce hybrid CNT sheets. Microstructure characterization was performed using scanning electron microscopy, and the Wiedemann–Franz law was used to characterize transport properties. The resulting hybrid sheets exhibited improved electrical conductivity, thermal conductivity, and EMI-shielding effectiveness compared to pristine CNT sheets. X-band EMI-shielding effectiveness improved by over 200%, while electrical conductivity improved by more than 1500% in the hybrid sheets due to a higher charge-carrier density and synergistic effects between nanomaterials. The addition of AgNW to CNT sheets resulted in a large improvement in electrical conductivity and EMI shielding; however, this may also result in increased weight and sample thickness. Similarly, the addition of MXene to CNT sheets may result in an increase in weight due to the presence of the denser MXene flakes.

Ultrafine Fe-Mn bimetallic nanoparticles anchored in nitrogen-doped carbon nanofiber electro-Fenton membrane with strong metal-support interactions for sustainable water decontamination in wide pH ranges

Designing a membrane electrode with high activity and anti-scaling ability in a wide pH range is crucial to the development of flow-through electro-Fenton system. Herein, we reported a novel porous membrane composed of ultrafine FeMn bimetallic nanoparticles anchored in nitrogen-doped carbon nanofibers (FeMn/N-CNF) obtained through a facile electrospinning-carbonization process. The strong metal-support interaction (SMSI) phenomena including carbon encapsulation structure and electron transfer from metal to N-CNF, beneficial to the intrinsic activities, were successfully induced by the enhanced interfacial metal-nitrogen bonding in FeMn/N-CNF. Microstructural characterizations and leaching test revealed that the SMSI encapsulation structure could promote the formation of ultrafine FeMn nanoparticles in N-CNF during the high-temperature carbonization process and prevent leaching of active Fe/Mn metals into solution across a wide pH range. The constructed gravity-driven flow-through electro-Fenton system based on a FeMn/N-CNF cathode membrane exhibited superior performance to generate H2O2 (36.23 mmol L-1 h-1) and subsequent activate H2O2 decomposition to hydroxyl radicals (0.1024 min-1), achieving remarkable degradation efficiencies of 96.8%, 92.3%, and 90.3% within 60 min for Rhodamine B, Tetracycline, and Methyl Orange, respectively. Furthermore, the FeMn/N-CNF membrane filter demonstrated good pH adaptability, excellent cycle stability and anti-scaling ability during the degradation process. This work offers a viable avenue to enhance degradation performance and environmental robustness for practical water decontamination via achieving SMSI effect in carbon-supported electro-Fenton membranes.

Quantitative mechanism of abnormal hardening behavior of Ti6Al4V alloy strengthened by ultrasonic surface rolling

In general, the outermost region of a metallic material has the highest hardness after surface mechanical strengthening. However, an abnormal surface hardening behavior was observed in Ti6Al4V alloy after the ultrasonic surface rolling process (USRP) in this work. The region with the highest surface hardening was not at the top surface but at the subsurface. By analyzing the distribution of grain size, dislocation density, texture, and kernel average misorientation (KAM) at different depths from the surface, and combining these findings with finite element analysis (FEA), the microstructural evolution underlying this abnormal surface hardening was elucidated. The microstructural characterization and FEA results indicate that the subsurface region underwent the most significant deformation. Subsequently, through the application of theoretical analysis, the potential mechanism of abnormal hardening of USRP treatment is described quantitatively for the first time. The results demonstrated that the hardening effect resulting from grain refinement was less pronounced, whereas the hardening effect resulting from dislocation pile-up was more prevalent. At the subsurface region of the USRP sample, a large number of interfaces resulted in the highest accumulation of dislocations in this area. Consequently, the subsurface region exhibited the highest microhardness, leading to the abnormal surface hardening phenomenon.

Crevice corrosion behavior of 316L austenitic steel in static liquid lead-bismuth eutectic at 550°C

Crevice corrosion is a significant form of localized corrosion that can lead to failures in structural components. However, there is a lack of research on this phenomenon in liquid lead-bismuth eutectic (LBE). In this study, the crevice corrosion behavior of 316L exposed to stagnant LBE with the oxygen concentration of 1 × 10-6 wt.% at 550°C for 500 h was examined for the first time. Microstructural characterizations indicated 316L is susceptible to crevice corrosion and reducing the crevices size facilitates a transition from oxidation to dissolution corrosion. Grain boundaries are able to provide more diffusion channels for oxygen, thereby promoting the development of Cr-rich oxides and chemical segregations beneath the surface scale. A simplified model elucidating the transportation of dissolved oxygen within the crevice environment of LBE has been developed.

Low‐Cycle Fatigue Performance of Directed Energy Deposited and Conventionally Manufactured Hybrid Gas Tungsten Arc‐Welded Duplex Stainless Steel Joints

Arc‐directed energy deposition (DED‐Arc) is a technology for the production of complex and large‐scaled components. It benefits from high deposition rates and low investment costs. However, to further expand the applications of additively manufactured parts, the possibility for implementation in conventionally manufactured assemblies is crucial. Therefore, this study focusses on the structural integrity of welded joints of DED‐Arc and as‐rolled duplex stainless steels and the welded and nonwelded as‐rolled benchmark. While the fraction of the constituents is almost balanced in the as‐rolled condition, the amount of austenite in the DED‐Arc specimens exceeds 60%. The similar weldment is predominantly ferritic and the hybrid welded joint contains ≈30% austenite, which is discussed based on the nickel concentration. Results from microstructure characterization are correlated to the superior yield and ultimate tensile strength of the as‐rolled condition. Under total strain‐controlled fatigue experiments, the hybrid welded joints exhibit enhanced fatigue lives at various strain amplitudes while the base material shows lowest fatigue resistance. Computed tomography and fractography conclude that the structural integrity is not governed by inherent defects, but instead the phase ratio and distribution yield significant differences in the cyclic deformation response as well as an asymmetry of the hysteretic stress–strain behavior.

Experimental study on the chemical heat storage performance of nanoporous carbon based MgO/Mg(OH)2 composite by calcination method

The application of MgO/Mg(OH)2 in heat storage technology has been limited due to slow hydration rate and easy agglomeration. In this paper, nanoporous carbon particle (NCP) as a carrier was used to prepare NCP/MgO chemical heat storage composite materials by impregnation and calcination methods, respectively. The microstructure characterization, hydration reaction, and simultaneous thermogravimetric analysis experiments were carried out on the prepared composite materials. The results showed that the internal distribution of MgO in the composite material prepared by calcination method was more uniform, and the particle size of MgO was smaller. Under the conditions of 110 ℃ hydration temperature and 57.8 kPa water vapor partial pressure, the hydration conversion ratio of the composite material prepared by calcination method after 120 min of hydration conversion ratio reached 93 %, which was 17.7 % higher than that of the impregnated composite material and 50 % higher than that of pure MgO. Under the comprehensive influence of specific surface area, pore structure, and active component particle size, compared with pure materials and impregnated composite materials, the dehydration rate of the composite material prepared by calcination method at 300 ℃ was twice that of impregnated method and 6 times that of pure MgO, and the heat storage density reached 1039kJ/kg. After 10 cycles, the heat storage density still maintained an initial state of 95.8 %. Compared with pure materials and impregnated composite materials, NCP/MgO composite materials prepared by calcination method had better heat storage performance and higher cyclic stability.

Enhancement of Corrosion, Biocompatibility and Drug Delivery Properties of Nitinol Implants Surface by Al-Zn-LDH Nanohybrids

This study investigates the enhancement of drug delivery and corrosion resistance by incorporating dexamethasone sodium phosphate into aluminum-zinc layered double hydroxide (LDH) coated nickel-titanium alloys. The nickel-titanium samples were fabricated from titanium and nickel powders using spark plasma sintering (SPS) and cold press sintering (CPS), followed by electrophoretic deposition of LDH nanoparticles. This composite construction aims to utilize the biocompatibility and mechanical properties of nickel-titanium, combined with the controlled drug release and corrosion resistance properties of LDH coatings. Structural and microstructural characterizations were performed using X-ray diffraction and scanning electron microscopy. The results indicated that SPS samples exhibited superior microstructural homogeneity and corrosion resistance compared to CPS samples. Dexamethasone sodium phosphate was successfully intercalated into the LDH layers, as evidenced by an increase in layer spacing from 7.14Å to 20.130Å. The LDH-coated nickel-titanium with intercalated dexamethasone sodium phosphate demonstrated a 5% lower drug release rate and significantly improved corrosion resistance compared to uncoated samples. Cell adhesion studies confirmed good biocompatibility between cells and the coated surface. This composite material shows promise for enhanced performance in biomedical applications, particularly in drug delivery and corrosion resistance.

Microstructural characterization and creep behavior of dispersion strengthened MRI230D magnesium alloy

The microstructural changes following the dispersion of SiC nanoparticles (SiCnp) and its subsequent significance on the creep response of MRI230D alloy are examined. Nanocomposites (NCs) of MRI230D alloy are fabricated with a dispersion of 1.0SiCnp (NC1SiC) and 2.0SiCnp (NC2SiC) (wt.%) using squeeze-casting. The primary Mg (α-Mg), lamellar C36 (Mg,Al)2Ca, as well as blocky Al8Mn5 phases, are observed in the MRI230D alloy and NCs. Additionally, SiC phase is detected in NCs. The additions of SiCnp refine the grains of the NCs. The fraction of C36 increases with an increase in SiCnp in MRI230D alloy. The alloy and NCs are exposed to impression creep tests under 450 to 500 MPa stress and 448 to 498 K temperature. The NCs exhibit better resistance to creep over MRI230D alloy, and NC2SiC is the most creep-resistant. The strengthening from the increased fraction of C36, along with Orowan strengthening from SiCnp dispersion in the α-Mg matrix, give rise to improved creep strength of the NCs than the alloy. The creep in MRI230D alloy and NCs progressed by dislocation-climb with pipe diffusion.

Enhancing corrosion fatigue performance of 17-4 PH stainless steel by simultaneous aging and plasma nitriding

This study investigated the effects of simultaneous aging and low-temperature plasma nitriding on the corrosion fatigue performance of 17-4 PH stainless steel. Plasma nitriding was conducted under two temperatures of 400 and 500 °C and, for comparison, some other specimens were subjected to aging treatment at the same temperatures and times. Microstructural characterization by scanning electron microscope (FESEM) and electron backscatter diffraction (EBSD) confirmed similar structures at the core in the nitrided and aged specimens, thereby, the influence of nitrogen at the surface of 17-4 alloy could be carefully investigated. X-ray diffraction and grazing incidence X-ray diffraction (GIXRD) identified expanded martensite as the matrix within the nitrided layer, accompanied by CrN, Fe3N, and Fe4N phases. X-ray photoelectron spectroscopy (XPS) analysis revealed high nitrogen concentration, in regions very close to the surface, after nitriding at 500 °C. The N1s spectra shifted towards lower binding energies, indicating interaction between nitrogen and the matrix atoms, and the formation of nitrides in the nitrided layer. The nitrided thicknesses experienced close values at 400 °C (10 h) and 500 °C (5 h), provided at 400 °C the layer was mostly a supersaturated solid solution but at 500 °C it was composed of iron nitrides and chromium nitride. High hardness values of above 1600 HV0.1 were obtained after optimum plasma nitriding as the result of combined effects of solution strengthening induced by nitrogen atoms and the presence of dispersed nitride phases. EBSD results indicated residual stress within the nitrided layer, which would affect the corrosion fatigue resistance. Experimental findings demonstrated that both aging and plasma nitriding substantially enhanced the corrosion fatigue resistance of 17-4 PH stainless steel in 3.5 wt% NaCl. Moreover, simultaneous aging and plasma nitriding proved superior behavior in corrosion fatigue, primarily due to delayed crack initiation and improved fatigue resistance, without the risk of overaging which is detrimental to mechanical properties.