Materials Characterization最新文献

{"title":"Molten salt-assisted controlled synthesis of two-dimensional molybdenum carbide","authors":"","doi":"10.1016/j.matchar.2024.114412","DOIUrl":"10.1016/j.matchar.2024.114412","url":null,"abstract":"<div><div>The present investigation examines the carbothermal reduction synthesis of two-dimensional molybdenum carbide (2D Mo₂C) using sodium carbonate (Na₂CO₃) as a molten salt diffusion promoter and sodium sulfide (Na₂S) as a solid-state intercalation agent. Raw molybdenum disulfide (MoS₂) powder undergoes carbothermal reduction facilitated by activated carbon and Na₂CO₃ above 800 °C to produce 2D Mo₂C layers intercalated by Na₂S. The diffusion of Na₂S can be enhanced by the fluidity of molten salt Na₂CO₃, leading to the expansion of the Mo₂C layer spacing to 29 nm under the influence of the temperature field. Na₂S intercalation prevents layer shrinkage during cooling while molten Na₂CO₃ directs 2D growth, yielding 10 nm-thick sheets. The product maintains hexagonal β-Mo₂C structure up to 950 °C with microflowers of accordion-shaped nanosheets. Ultrasonication exfoliates the weakly bound Mo₂C layers into uniform, freely suspended flakes around 10–100 nm in lateral size. This work demonstrates the tuning of 2D Mo₂C morphology in high-temperature reactions by utilizing molten salts. The principal results are the synthesis of micrometer-sized Mo₂C sheets with controlled nanoscale thickness and uniform nanosheet dispersions, enabled by molten salt-directed diffusion of intercalated species. The major conclusion drawn is that solid-liquid synergistic diffusion can guide precision synthesis of layered nanomaterials.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142319705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CALPHAD-aided design for superior mechanical behavior in Ti40Zr20Hf40-xCrx eutectic refractory high-entropy alloys","authors":"","doi":"10.1016/j.matchar.2024.114393","DOIUrl":"10.1016/j.matchar.2024.114393","url":null,"abstract":"<div><div>TiZrHf-based refractory high entropy alloys (RHEAs) are becoming the focus in advanced metal materials owing to the excellent mechanical properties under the condition of medium and high temperatures. Nevertheless, the strength of TiZrHf-based RHEAs at medium temperatures has hindered the further application. This work proposed a novel approach to improve the mechanical properties of TiZrHf-based RHEAs. An innovative series of Ti₄₀Zr₂₀Hf_40-xCr_x (x = 19, 24 and 29, denoted by HfCr19, HfCr24 and HfCr29, respectively) eutectic refractory high entropy alloys (ERHEAs) were designed and prepared. The designed Ti₄₀Zr₂₀Hf_40-xCr_x alloys can form lamellar eutectic structure including BCC/HCP phase and Laves precipitating phase in solidification with the decrease of Hf/Cr ratio. The microstructure of HfCr19 and HfCr24 alloys was composed of BCC, HCP and Laves phase, while the HfCr29 alloy consisted of BCC and Laves phase. The formation of HCP phase in the Ti₄₀Zr₂₀Hf_40-xCr_x alloy were attributed to the lattice of Ti_0.5Zr_0.5 phase reconstruction during the rapid cooling, which promoted the formation of isomers in the alloy. Hence, the part of BCC phase was transformed into HCP phase in the HfCr19 and HfCr24 alloys, and the lamellar eutectic structure consisted of BCC/HCP phase and Laves phase. In addition, compared with the near-eutectic HfCr19 and HfCr29 alloys, the HfCr24 alloy with a complete lamellar eutectic structure has higher compressive strength at room temperature, which can reach 1648.7 MPa. In addition, the compressive strength (1261.7 MPa) can still be achieved at 600 °C. This work successfully prepared a high-strength TiZrHf-based ERHEA, and the compression mechanical properties at room temperature and middle-high temperature were studied and analyzed.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142323982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Generation of micrograph-annotation pairs for steel microstructure recognition using the hybrid deep generative model in the case of an extremely small and imbalanced dataset","authors":"","doi":"10.1016/j.matchar.2024.114407","DOIUrl":"10.1016/j.matchar.2024.114407","url":null,"abstract":"<div><div>Insufficient annotated samples coupled with class imbalance problem largely restrict the wide application of deep learning (DL)-based approach in microstructure recognition and quantification. In this work, we present a micrograph augmentation approach using the hybrid deep generative model to generate SEM image-annotation pairs for the establishment of a large-scale and well-balanced augmentation dataset. In this method, a generator is established to produce the desired annotations and then a translator is trained to translate these synthetic annotations into high-quality SEM images. The proposed method is successfully applied to an extremely small and imbalanced additively manufactured (AM) steel dataset containing only one SEM image-annotation pair with a very low martensite/austenite (MA) fraction, to significantly augment the initial dataset and achieve a more balanced distribution of phase fraction. The effectiveness of the present method is well demonstrated by the fact that the extensibility of microstructure recognition model to unseen micrographs is improved through the utilization of synthetic data. Furthermore, the impact of synthetic data proportion on the model's performance and the underlying reasons for synthetic data to improve the extensibility of trained models are also discussed in detail.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142328058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating scandium-alloyed NbSi systems: Microstructure, oxidation behavior, and fracture toughness","authors":"","doi":"10.1016/j.matchar.2024.114409","DOIUrl":"10.1016/j.matchar.2024.114409","url":null,"abstract":"<div><div>In order to synchronize the oxidation resistance and room temperature fracture toughness of Nb<img>Si based alloys to meet the development needs, the effects of Sc addition on microstructure evolution, oxidation resistance and mechanical performance of Nb-16Si-20Ti-1.5Zr-1C-1B-<em>x</em>Sc (<em>x</em> = 0, 0.1, 0.3, 0.5, 0.8) alloys are studied systematically. All compositions of the alloys are composed of two phases, Nbss and γ-(Nb,X)₅Si₃, X-ray diffraction and electron microscopy reveal that Sc addition refines γ-(Nb,X)₅Si₃ phases and promotes a transition from primary to lamellar eutectic structures, enhancing oxidation resistance. Sc₂O₃ formation at phase boundaries impedes oxygen diffusion, forming continuous oxide barriers (TiO₂ and SiO₂), thereby improving oxidation resistance. Mechanical testing shows an increase in fracture toughness with Sc doping, attributed to enhanced crack deflection and energy absorption within the Nbss phase. These results are important for the simultaneous improvement of room-temperature fracture toughness and high-temperature oxidation resistance as well as the mechanism of action of the rare earth element Sc, and for the further development of Nb<img>Si based superalloys to meet practical needs.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142314567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of temperature on creep aging behavior of the nugget zone of AA2195 AlLi alloy produced by friction stir welding","authors":"","doi":"10.1016/j.matchar.2024.114408","DOIUrl":"10.1016/j.matchar.2024.114408","url":null,"abstract":"<div><div>This paper aims to study the effect of temperatures on the creep aging behaviors of the nugget zone (NZ) of Al<img>Li alloy by friction stir welding (FSW). The results suggest that the creep strain of the NZ experiences a significant increase as the temperature rises, surpassing that of the base material (BM) at equivalent temperatures. In the case of NZ, the elevation of temperature from 160 to 190 °C induces a pronounced increase in both the size and volume fraction of the T₁ phase, which results in a substantial enhancement in the strength. In contrast, the peak-aged strengths of the BM exhibit minimal variation in this temperature range. As the temperature increases, the time required for the BM to reach its peak aging state significantly decreases, whereas the changes in the NZ are less pronounced. For the NZ, the time required to reach the peak aging state is obviously longer than that for the BM. Although the average length of the T₁ phase in the NZ is markedly greater than that in the BM, its volume fraction and number density in the NZ are considerably lower than those in the BM, resulting in inferior strength reinforcement in the NZ compared to the BM after creep aging.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142323983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Solute-induced transition in Poisson's ratio and strength: A phenomenon in additively manufactured Al-Si-Mg alloys","authors":"","doi":"10.1016/j.matchar.2024.114384","DOIUrl":"10.1016/j.matchar.2024.114384","url":null,"abstract":"<div><div>In this study, cubic coupons of AlSi10Mg alloy were printed using the laser powder bed fusion (LPBF) technique. The effect of heating/reheating cycles on solute trapping and partitioning of alloying elements was investigated using atom probe tomography and transmission electron microscopy. Nano-hardness analysis and uniaxial tensile tests equipped with digital image correlation were employed to investigate the mechanical properties and Poisson's ratio. X-ray micro-computed tomography was utilized to detect strain localization sites along the building direction. Also, the uniaxial tensile test was simulated using finite element analysis to verify the experimental data and predict stress triaxiality. The results showed that the solute trapping and partitioning during the LPBF process results in remarkable changes in phases, their size and morphology, Poisson's ratio, strengthening factor, and consequently mechanical properties. While the tensile sample from top part of the LPBF coupon mostly shows porosity due to floating and entrapment of gases during layer-by-layer fusion/solidification, the sample from bottom part is exposed to sub-surface microcracking induced by residual stresses. The hardness, elastic, and shear moduli, Peierls stress, and cumulative strain energy of the top-part sample are higher than those of the bottom-part sample even though electron backscatter diffraction analyses report similar grain size and texture. Besides, by distancing from the build plate, the Poisson's ratio decreases. Simulation results of both samples indicate that the middle of the gauge is a high-potential area of failure initiation, where the bottom-part sample shows higher stress localization.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Si-doped BCC-based high-entropy alloy to overcome soft magnetic–mechanical properties trade-off via coherent B2 nanoprecipitates","authors":"","doi":"10.1016/j.matchar.2024.114402","DOIUrl":"10.1016/j.matchar.2024.114402","url":null,"abstract":"<div><div>The trade-off between magnetic property and mechanical property usually occurs in traditional soft magnetic materials (SMMs) because the strengthening strategy (e.g. precipitation hardening) can worsen soft magnetic properties through the hindrance of magnetic domain wall motion. This dilemma is overcome in current work by developing the FeCoNiAlSi_0.01 (Fe_24.94Co_24.94Ni_24.94Al_24.94Si_0.24 in at.%) high-entropy alloy (HEA) (termed as Si0.24 HEA) with excellent soft magnetic performance and attractive mechanical property through coherent B2 nanoprecipitates (6 nm) distributed in body-centered-cubic (BCC) matrix. The atom probe tomography (APT) result shows that the B2 nanoprecipitates have similar composition to the BCC matrix. The Si0.24 HEA shows small width of domain branching and low anisotropy constant leading to the optimum alternating current (AC) soft magnetic properties. The respective total loss (AC P_s), the coercivity (AC H_c), and the eddy current loss (P_e) at 950 Hz of the Si0.24 HEA are 21.20 W/kg, 230 A/m, and 16.25 W/kg, which is reduced by 45 %, 44 %, and 48 % compared with the FeCoNiAl (Si-free HEA). The Si0.24 HEA shows good mechanical property with the yield strength of 987 MPa and engineering strain of 30 %, which is 12 % and 1.3 times higher than that of the Si-free HEA. Moreover, the current studied HEAs exhibit high saturation magnetization (M_s = 108–115 Am²/kg) and Curie temperature (T_C = 1053–1097 K, larger than T_C of Fe (1043 K)), which indicates their perspective high-temperature applications as novel SMMs for the need of modern power electronics and electrical machines.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357122","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Altered microstructure, phase transformation behaviors and shape memory response of CuAlMn shape memory alloys fabricated by selective laser melting","authors":"","doi":"10.1016/j.matchar.2024.114398","DOIUrl":"10.1016/j.matchar.2024.114398","url":null,"abstract":"<div><div>In this paper, nearly defect-free CuAlMn SMAs were successfully fabricated by selected laser melting (SLM). The result of microstructure show that only one type of thermal-induced martensite was detected in the prepared specimens, and the process parameters play a vital role in phase transformation behaviors. The alloy shows excellent ultimate tensile strength of 820 MPa and elongation of 11.5 %. Furthermore, the high shape memory response, i.e. shape recovery rate of 91.4 %–99.6 %, shape memory strain of 2.59 %–5.46 %, was presented under compressive strain not exceeding 8 %.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In-situ EBSD study of the active slip systems and substructure evolution in a medium-entropy alloy during tensile deformation","authors":"","doi":"10.1016/j.matchar.2024.114405","DOIUrl":"10.1016/j.matchar.2024.114405","url":null,"abstract":"<div><div>Electron backscatter diffraction (EBSD) coupled with in-situ tensile loading is powerful for investigating the microstructural evolution of alloys. Thermo-mechanically treated f.c.c. medium-entropy alloys (MEAs) typically have high densities of annealing twin boundaries (ATBs), which can not only strengthen but also toughen the MEA via interacting with dislocations. However, the evolution of ATBs and other substructures in plastically-deformed MEA has not yet been revealed. Plastic deformation involving dislocation evolution, active slip systems, lattice rotation, boundary transformation, and grain subdivision in a polycrystalline MEA Ni_41.4Co_23.3Cr_23.3Al₃Ti₃V₆ was studied using in-situ EBSD. The slip was accompanied by heterogeneous lattice rotation among grains and within grains, where inhomogeneous plasticity was accommodated by geometrically-necessary dislocations (GNDs). Both GND and low-angled boundaries (LABs) densities substantially increased with progressive strain, which was mainly concentrated in sites approaching ATBs or grain boundaries (GBs). Located stress, lattice rotation, or curvature caused a loss in the coherence of ATBs, which resulted in integrity loss with increasing strain and promoted a decrease in density by 60 %. Further, lattice rotation incompatibility due to constraints from neighboring grains leads to grain fragmentation into various misorientated volumes, which were separated by LABs or high-angle boundaries (HABs). The grain orientation angle increased with progressive strain and crystallographic 〈111〉 orientation gradually spread toward a tensile direction. Slip systems with maximum Schmid factor were activated first at ε ≥ 3.9 %, which is almost the same with experimental slip traces. Both single slip and double slip occurred during plasticity, where straight slip traces tend to curve due to lattice curvature. Slip transfers are not only controlled by geometric compatibility factor, which can occur between some neighboring grains with low geometric compatibility factor but high Schmid factor.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142319704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cryogenic tribological behavior of coarse, ultrafine grained and heterogeneous Fe-18Cr-8Ni austenitic stainless steel","authors":"","doi":"10.1016/j.matchar.2024.114406","DOIUrl":"10.1016/j.matchar.2024.114406","url":null,"abstract":"<div><div>Commonly used austenitic stainless steels (ASSs) have some limitation in sliding wear conditions due to their relatively low yield strength and hardness. To improve the wear resistance, three kinds of microstructure (coarse grain (CG), heterogeneous structure (HS), and ultrafine grain (UFG)) are prepared, to investigate the grain size on the dry sliding tribological behavior, as well as wear mechanisms of Fe-18Cr-8Ni ASSs at room temperature (RT) and cryogenic temperature (−120 °C). The results indicate that at RT the UFG specimen exhibits the lowest wear rate during the wear tests, where the wear mechanisms are mainly oxidation wear and abrasive wear. While, when tested at −120 °C, the CG specimen exhibits the best wear resistance compared with that of the other two specimens due to its superior plastic deformation ability and strain hardening ability. Moreover, the HS specimen exhibits the lowest coefficient of friction (CoF), which is due to the abrasive particles generated on the contact surface provide a certain level of friction reduction, while the wear rate increases as these particles serve as third-party abrasives, which further removing material.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142314565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}