Microstructure Properties Research Articles

Experimental investigation of additively manufactured MS-300 maraging steel samples: Microstructure and mechanical properties

Experimental investigation of additively manufactured MS-300 maraging steel samples: Microstructure and mechanical properties

Characterization of different size reinforcement effects on microstructural failure mechanism in carbon nanotube-reinforced aluminum composites

In this study, we investigated the effect of reinforcement sizes on the tensile strength and ductility of carbon nanotube (CNT)-reinforced aluminum matrix composites fabricated through ball milling, followed by hot extrusion of a powder encapsulated in an aluminum container. We analyzed the microstructural properties of the samples, including the aluminum grain size, its spatial variation with the alignment of CNT, and CNT length. Nanoindentation test results revealed the spatial variation of hardness and Young’s modulus of composites with small-diameter CNTs, indicating local Al4C3 formation and interlock structure resulting from dislocation accumulation during the fabrication process. This explains dimples of different sizes observed on the fracture surfaces of the samples and the occurrence of CNT pullout. Furthermore, we proposed the failure mechanism of the composites under tensile strain and calculated the failure strain using the Whitehouse–Clyne model. The calculated failure strain agrees well with the experimental values. The high ductility of the composites is attributed to the large grain fracture and rotation of neighboring grains due to the constraint imposed by CNTs.

Interface Microstructure and Mechanical Properties of Nickel/Steel Bimetal Composite Pipe Fabricated by Explosive Welding

In this paper, the microstructure and mechanical properties at the interface of Incoloy825/X65 bimetallic composite pipe achieved by explosive welding were systematically studied. Results show that a periodic wavy bonding interface was formed between the Incoloy825 and X65 due to the jets caused by the high-impact stresses during explosive welding, which was beneficial for improving the bonding strength of the Incoloy825 and X65. Atomic diffusion and localized melting occurred near the interface during explosive welding. Some fine crystal grains were generated in the vicinity of the interface due to the strong plastic deformation and dynamic recrystallization, whereas some elongated grains growing in the perpendicular direction to the interface were found in the wider localized melted zone. Room temperature nanoindentation test showed that due to the existence of fine grains resulting from the recrystallization at the interface, the hardness of the interface was higher than that of the base metals. Voids and defects were prone to appearing in the vortex regions near the interface, where the weak point in the interface was located.

Investigations on Microstructure, Mechanical, and Wear Properties, with Strengthening Mechanisms of Al6061-CuO Composites

Metal matrix composites (MMCs) reinforced with Copper Oxide (CuO) and Aluminum (Al) 6061 (Al6061) alloys are being studied to determine their mechanical, physical, and dry sliding wear properties. The liquid metallurgical stir casting method with ultrasonication was employed for fabricating Al6061-CuO microparticle-reinforced composite specimens by incorporating 2–6 weight percent (wt.%) CuO particles into the matrix. Physical, mechanical, and dry sliding wear properties were investigated in Al6061-CuO MMCs, adopting ASTM standards. The experimental results show that adding CuO to an Al6061 alloy increases its density by 7.54%, hardness by 45.78%, and tensile strength by 35.02%, reducing percentage elongation by 40.03%. Dry wear measurements on a pin-on-disc apparatus show that Al6061-CuO MMCs outperform the Al6061 alloy in wear resistance. Al6061-CuO MMCs’ strength has been predicted using many strengthening mechanism models and its elastic modulus through several models. The strengthening of Al6061-CuO MMCs is predominantly influenced by thermal mismatch, more so than by Hall–Petch, Orowan strengthening, and load transfer mechanisms. As the CuO content in the composite increases, the strengthening effects due to dislocation interactions between the matrix and reinforcement particles, the coefficient of thermal expansion (CTE) difference, grain refinement, and load transfer consistently improve. The Al6061-CuO MMCs were also examined using an optical microscope (OM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), and scanning electron microscopy (SEM) before and after fracture and wear tests. The investigation shows that an Al6061-CuO composite material with increased CuO reinforcement showed higher mechanical and tribological characteristics.

Changes in Microstructure and Mechanical Properties of Goryeo Dynasty Bronze Vessels with Manufacturing Process

Bronze vessels are manufactured using casting and forging techniques, and various microstructures can be observed depending on the manufacturing process. In this study, we confirmed mechanical properties and microstructural evolution in the manufacturing process by observing the microstructures and composition analysis of 18 bronze vessels in the Goryeo Dynasty excavated from historical sites. The results show that 13 of the bronze vessels were manufactured using a Cu-Sn alloy with a Sn content of 20 to 24 wt%. The α phase and β(M) phase were observed, indicating that hot forging and quenching treatment were performed after casting. 3 bronze vessels were produced from a Cu-Sn-Pb alloy, and considering that the α phase and α+δ phase were observed, it could be seen that the process was completed by slow cooling after casting. The correlation between the type of bronze vessel and the manufacturing process has not been confirmed, except of ewer. It was confirmed that various microstructures were created depending on the manufacturing process and that the mechanical properties also changed. Bronze vessels composed of the α phase and α+δ phase due to the casting process had lower Vickers hardness values compared to bronze vessels that showed the quenched β(M) or γ phase. Electron backscatter diffraction (EBSD) phase analysis and kernel average misorientation (KAM) were performed using six bronze vessels composed of α and β(M) phases. The results showed that the factors affecting hardness were the ratio of the β(M) phase and the KAM value. However, it could not be confirmed to what extent the ratio of the β(M) phase and KAM value affected the improvement in mechanical properties.

Microstructure, Corrosion Resistance and Tensile Properties of Modified Al-0.7Mn Alloy

A modified alloy (Al-0.7Mn) was designed and fabricated with an increased Mn content up to 0.7wt.% and a controlled Fe content of 0.1wt.% and compared with the conventional Al3102 (Al-0.3Mn) alloy using the air-slip casting process. Both alloys were homogenized at 510°C for 10 hours and then air-cooled. The microstructure, corrosion resistance, and mechanical properties of these materials were investigated. In the modified Al-0.7Mn alloy, the Mn/Fe ratios were found to be higher in both the α-Al matrix and the intermetallic compound of Al<sub>6</sub>(Mn, Fe) compared to those of the Al3102 alloy. Additionally, the size and volume fraction of the Al<sub>6</sub>(Mn, Fe) phase were relatively larger and higher in the modified Al-0.7Mn alloy, while the grain size of the α-Al matrix was significantly smaller. The galvanic corrosion test results indicated that the corrosion potential (E<sub>corr</sub>) of the conventional Al3102 alloy was higher than that of the modified Al-0.7Mn alloy (Al-0.7Mn: -682.1mV, Al3102: -652.4mV). In contrast, the corrosion current (I<sub>corr</sub>) and corrosion rate were measured to be 49.86 μA and 0.541 mm/year for the Al-0.7Mn alloy, and 53.91 μA and 0.585 mm/year for the Al3102 alloy, respectively. Thus, it was confirmed that the corrosion rate of the Al-0.7Mn alloy was slower compared to the conventional alloy, indicating better corrosion resistance. Room temperature tensile results showed that the tensile strengths of the modified and conventional alloys were 92.55 MPa and 78.39 MPa, respectively, demonstrating that the modified Al-0.7Mn alloy achieved higher strength without a significant decrease in ductility. This improvement is attributed to the higher Mn/Fe wt.% ratio in the Al<sub>6</sub>(Mn, Fe) phase of the modified Al-0.7Mn alloy, which can reduce the detrimental effect of Fe element and enhance the corrosion resistance. Additionally, the larger size and higher volume fraction of Al<sub>6</sub>(Mn, Fe) in the modified alloy, along with the smaller grain size, may contribute to the higher tensile strength. Based on these results, the corrosion mechanisms and deformation behavior of the modified Al-0.7Mn alloy were also discussed.

Heat treatment effect on the carbides in T-15 and M-4 steels

ABSTRACT In the present work, the effect of heat treatment on the microstructure and mechanical properties of T-15 and M-4 high-speed steels was investigated. These steels were produced by powder metallurgy. Due to their frictional wear resistance properties, T-15 and M-4 high-speed steels are widely used in the cutting tool manufacture of the metalworking industry. A heat treatment was applied to both steels, heating them to 1250°C, then air quenching and, finally tempering at 550°C for 2 h, 3 times (triple tempering at 550°C). Steels were characterized by hardness test, metallographic analysis, tensile strength test, and fracture analysis after the heat treatment. Results were compared and related to the metallurgical microstructure, mainly to the distribution of carbides, and also to fracture type and characteristics. Test results and chemical analysis showed important differences between T-15 and M-4 steels.

Effect of Al addition on the microstructure and magnetic properties of Fe73.5Si13.5M3B9Cu1 alloys

Effect of Al addition on the microstructure and magnetic properties of Fe73.5Si13.5M3B9Cu1 alloys

Comparison of Novel 1 GPa Low‐Carbon, Low‐Alloyed Steel Produced with Simulated and Laboratory‐Scale Thermomechanical Controlled Processes

A laboratory‐scale hot‐rolled Ti–Mo–V–Nb steel with 1 GPa tensile strength is produced, and its microstructure and tensile properties are characterized using advanced analysis techniques and uniaxial tensile testing. A Gleeble 3800 thermomechanical simulator is used to determine a process window for the thermomechanical controlled processing (TMCP) procedure. Although the simulated TMCP specimens are fully ferritic at coiling temperatures (CT) of 590 and 630 °C, the bainitic and mixed (bainitic + ferritic) microstructure is formed in the hot‐rolled steels. The variation in the microstructure causes variations in the dislocation density through the sheet thickness, which significantly reduces the steel's ductility properties, whereas a 16% elongation is achieved with the fully bainitic microstructure. Another significant difference between the simulated TMCP and hot‐rolled specimens is the precipitation behavior. No nanosized interphase‐precipitated (IP) carbides are formed in the hot‐rolled steel during the austenite‐to‐ferrite phase transformation, although the formation of the nanosized spherical IPs is observed within the polygonal ferrite grains of the simulated TMCP specimens at the CT of 630 °C. Relatively coarse (5–20 nm) spherical (V,Mo,Ti,Nb)C carbides do not strongly affect the tensile properties of the hot‐rolled Ti–Mo–V–Nb steel. The results show that the dislocation and grain boundary strengthening mainly contribute to the strength properties of this steel.

Effect of Yttrium Addition on Microstructure and Mechanical Properties of Sr-Modified Low-Si Cast Aluminum Alloy

Effect of Yttrium Addition on Microstructure and Mechanical Properties of Sr-Modified Low-Si Cast Aluminum Alloy

The impact of adding different levels of spirulina on the characteristics of halloumi cheese

The primary purpose of this study was to evaluate the effect of spirulina addition to the halloumi cheese characteristics. The spirulina-addition process involved using a homogenizer, with concentrations of spirulina powder at 0%, 0.5%, 1%, and 1.5% w/v. The microstructure, mineral, rheologic, color, texture, microbial loads, and sensorial properties of halloumi supplemented with spirulina were evaluated. The appearance of halloumi was affected by spirulina. Adding spirulina at least 0.5% could affect the overall color of halloumi (p < 0.01). The structural compactness of halloumi reduces as spirulina concentration rises (p < 0.05). Adding 1% and 1.5% of spirulina raises (p < 0.01) the amounts of minerals (P, K, S, Ca, and Mg). Spirulina fortification significantly impacted the hardness, cohesion, springiness, gumminess, and chewiness of halloumi cheese (p < 0.05) but did not differ in adhesiveness and resilience. Regarding microbial loads, halloumi-spirulina cheese was safe from pathogenic contamination. Panelists concluded that there was no significant differentiation in halloumi cheese color, flavor, or taste. However, 0% and 0.5% addition levels were more acceptable than 1% and 1.5% (p < 0.05). Adding spirulina powder during halloumi cheese processing led to unique colors and characteristics. The mineral compositions, rheology, and texture of the halloumi cheese exhibit distinct characteristics, beginning with a 1% spirulina addition. However, the favorite taste of halloumi cheese was 0% and 0.5%, which are additional levels of spirulina.

Heterogeneous interfaces of aluminum bronze/Inconel 718 dissimilar alloys under different wire arc directed energy deposition sequences

Abstract The layer-by-layer deposition strategy of additive manufacturing makes it ideal to fabricate dissimilar alloy components with varying functionality, which has promising application potential in a large number of industrial areas. In this study, two components composed of ERCuAl-A2 aluminum bronze (CuAl9) and Inconel 718 nickel-based superalloy were fabricated with different deposition orders by wire-arc directed energy deposition. Subject to changes in heat input and thermophysical properties of the substrate, the transition region of the deposited Cu–Ni component with the bottom half of CuAl9 and the top half of Inconel 718 is narrow and serrated. This region features a laminated intermetallic compound layer due to the convection and rapid cooling in the molten pool. In contrast, the Ni–Cu component deposited in the opposite order exhibits a 2 mm gradient transition zone. Within this region, a large number of diverse precipitates were found as well as regional variations in grain size due to the multi-layer partial remelting. Both two components show strong bonds and their tensile specimens tested along the vertical direction always fracture at the softer CuAl9 side. Excellent tensile properties along the horizontal direction were obtained for Cu–Ni (Ultimate tensile strength: 573 MPa, yield stress: 302 MPa, elongation: 22%), while those of Ni–Cu are much lower due to the existence of the solidification cracks in the transition zone. The results from this study provide a reference for the additive manufacturing of Cu/Ni dissimilar alloy components, as well as their microstructure and mechanical properties control.

Impact of debranning on the nutritional, cooking, microstructural characteristics of five Indian small millets

BackgroundMillets are underutilized grains rich in nutrients. This study aimed to investigate the impact of debranning on the nutritional, cooking, and microstructural properties of five Indian millets namely foxtail, little, kodo, barnyard, and proso millet.MethodsThe proximate composition, mineral content, cooking properties (cooking time, solid loss, water uptake, alkali score), Fourier Transform Infra Red (FTIR) spectra, X ray Diffraction (XRD) and microstructural characteristics (Scanning Electron Microscopy) of dehusked and debranned millet samples were examined and analysed.ResultsDebranning resulted in decrease in protein (except for little and barnyard millets), dietary fibre, fat, mineral and phytate content in all the millets while enhanced available carbohydrates and amylose content. The cooking times for dehusked millets were significantly higher while, the solid loss and water uptake during cooking of debranned millets were higher. On debranning, Fourier Transform Infra Red (FTIR) spectra showed changes in the pattern with increase in the intensity of amide II (1363 to 1367 cm−1) and amide III (1215 to 1231 cm−1) bands in the debranned foxtail, little, and kodo millets. The X-ray diffractogram (XRD) showed decrease in relative crystallinity on debranning. Scanning Electron Microscopic (SEM) examination revealed that debranning resulted in the loss of seed coat, aleurone layer and partial loss of germ in the millets.ConclusionDehusked millets are nutritious and should be promoted in Indian diets to improve diet quality, debranned millets are nutritionally inferior, can increase the glycemic load of Indian diets.

Effect of Nanoclay Addition on Mechanical and Microstructure Properties of E-Glass Fiber and AA2022 Metal Skin Reinforced Epoxy Laminates

Effect of Nanoclay Addition on Mechanical and Microstructure Properties of E-Glass Fiber and AA2022 Metal Skin Reinforced Epoxy Laminates

Influence of Hot Rolling on Microstructure, Corrosion and Mechanical Properties of Mg–Zn–Mn–Ca Alloy

The effect of hot rolling on the microstructure, mechanical, and corrosion properties of the magnesium alloy 96 wt% Mg–2.3 wt% Zn–0.7 wt% Ca–1 wt% Mn was studied. After heat treatment, the original plates of an as-cast alloy were rolled from a 7 mm thickness to a 0.2 mm thickness at two temperatures—300 or 400 °C. It has been established that increasing the rolling temperature from 300 to 400 °C increases the fraction of recrystallized grains in the microstructure and after rolling at 400 °C, the microstructure is fully recrystallized. The best strength–ductility balance of the alloy was obtained after rolling at 300 °C, with a high total percentage reduction of 93–97%: the yield stress, the ultimate tensile strength, and the elongation averaged at 285 MPa, 310 MPa, and 5%, respectively. The alloy after rolling, annealed at 400 °C, shows improved ductility but lower strength: the yield stress, the ultimate tensile strength, and the elongation were 200 MPa, 260 MPa, and 17%, respectively. The strong dependence of corrosion resistance on respect to rolling direction is observed, which can be reduced after heat treatment. The as-rolled alloy and the heat-treated alloy had low corrosion rates in Hanks’ solution of 0.54 and 0.19 mm/year, respectively.

Optimizing self-compacting concrete with steel slag and fiber additions: enhancing fresh, mechanical, durability, and microstructural properties

Optimizing self-compacting concrete with steel slag and fiber additions: enhancing fresh, mechanical, durability, and microstructural properties

Microstructural, mechanical, and wear properties of ultrasonic assisted stir casted A356 Alloy/AlN composite

The ultrasonic-assisted stir-casting method has effectively prepared A356 alloy/AlN composites. The ultrasonic treatment and integration of AlN particles are shown to greatly enhance the mechanical and wear characteristics of the matrix via grain refinement. By incorporating 9 vol.% of AlN reinforced particles, the average grain size of A356 alloy was decreased from 36 μm to 10 μm. Additionally, the hardness and tensile strength experienced a respective rise of 60.6% and 32%. With an increase in the volume percentage of AlN particles, it is found that both the wear rate and the friction coefficient decreased. It is also observed that the A356 alloy displayed severe wear, whereas the composites exhibited moderate wear.

Fresh, hardened properties and microstructural analysis on the effect of NaOH molarities of industrial by-products based self-compacting geopolymer concrete

AbstractThe sodium hydroxide (NaOH) molarity in Self-compacting geopolymer concrete (SCGC) is essential for activating the precursor and aggregate to develop strength, workability, and microstructure. In this study, SCGC mixes prepared with 50% fly ash (FA) and 50% ground granulated blast furnace slag (GGBS) to investigate fresh and hardened properties with NaOH molarities (M) ranges from 8 to 16, the ratio of Na2SiO3 to NaOH kept constant at 2.5 and ratio of alkaline solution to the binder at 0.45 with 2% SP for the polymerization process. SCGC workability studies indicate the NaOH concentration increased, the slump flow decreased, and 14 M was the optimum molarity. The compressive, split tensile, and flexural strength results showed 39.4 MPa, 4.72 MPa, and 5.91 MPa at 28 days. The C–S–H gel enhanced the strength qualities studied from Fourier transform infrared spectroscopy. The scanning electron microscope showed microstructural densification of the entire system, which improved with the NaOH concentration, and the strength increased with the degree of polymerization and polycondensation. Hence, based on workability, the optimized NaOH concentration is 14 M with binder contents of FA (50%) and GGBS (50%). This study helps to improve the microstructure and strength properties with potential cost implications of SCGC.

Influence of Detonation Spraying Parameters on the Microstructure and Mechanical Properties of Hydroxyapatite Coatings.

The process of osteointegration depends significantly on the surface roughness, structure, chemical composition, and mechanical characteristics of the coating. In this regard, an important direction in the development of medical materials is the development of new techniques of surface modification and the creation of bioactive ceramic coatings. Calcium-phosphate materials based on hydroxyapatite have been proposed as bioactive ceramic coatings on titanium implants for the effective acceleration of bone tissue healing. To obtain bioactive ceramic coatings, pulse power sources are best suited, namely detonation spraying, in which the energy of the explosion of gas mixtures is used as a source of pulse action. The pulse mode of operation in the detonation spraying method is preferable for the formation of bioactive ceramic coatings. It provides a high velocity of hydroxyapatite particles, which promotes their effective fixation on the titanium substrate, while minimizing the heating of the material. This approach preserves the substrate structure and improves the coating adhesion. Four different types of coatings with varying O2/C2H2 molar ratios, ranging from 2.6 to 3.7, were obtained using detonation spraying. Powders and obtained coatings of hydroxyapatite were studied by Raman spectroscopy and XRD structural analysis. The results of XRD phase analysis showed the partial conversion of the hydroxyapatite phase to the α-tricalcium phosphate (α-TCP) phase during the detonation spraying process. The results obtained by Raman spectroscopy indicate that hydroxyapatite is the main phase in coatings. All hydroxyapatite-based coatings exhibited hydrophobic properties, which was confirmed by contact-angle values above 90° in wettability tests, characteristic of hydrophobic surfaces. The adhesive strength of the coatings was measured by the scratch test method. Tribological tests were conducted using the ball-on-disk method under both dry conditions and in Ringer's solution. This approach enabled the evaluation of wear resistance and friction coefficient of the coatings in different environments, simulating both lubrication-free conditions and those resembling physiological environments.

Effect of Combined Addition of La and Sm on Mechanical Properties, Microstructure Evolution, and Electrochemical Behavior of Mg-3Zn-1Mn/Sn-0.5Ca Alloy

The effects of the composite addition of La and Sm elements on the microstructural evolution, mechanical properties, and electrochemical behaviors of Mg-3Zn-1Mn/Sn-0.5Ca (wt.%) alloys are systematically investigated. The findings reveal that the Mg-3Zn-1Mn-0.5Ca alloy exhibits excellent ductility, achieving 26% elongation, whereas the Mg-3Zn-1Sn-0.5Ca alloy demonstrates good comprehensive mechanical properties. The addition of La and Sm results in a degree of grain refinement in both alloys and significantly bolsters the strength of the Mg-3Zn-1Mn-0.5Ca alloy, but it has a less pronounced effect on the mechanical properties of the Mg-3Zn-1Sn-0.5Ca alloy. Furthermore, the addition of La-Sm significantly improves the corrosion resistance of both alloys. Electrochemical impedance spectroscopy (EIS) analysis reveals that all four alloys form a double-capacitance loop morphology in 3.5% NaCl, indicating the formation of a protective film during the corrosion process. Among them, the Mg-3Zn-1Mn-0.5Ca-1La-0.5Sm alloy exhibits the largest capacitance loop radius, which is consistent with its polarization curve, indicating the best corrosion resistance. At the corrosion potential of −1.382V, the corrosion current is 8.97 μA·cm−2.