The zeolite ZSM-22 with different grain length and pore structure was synthesized by hydrothermal synthesis with TDPA as mesoporous template agent. The synthesized material was characterized using XRD, XRF, SEM, TEM, NH₃-TPD, N₂ adsorption/desorption, solid-state NMR, and Py-IR. The results indicated that the incorporation of TDPA is beneficial for the formation of the mesoporous structure and the optimization of the acidity distribution for the prepared ZSM-22 zeolite. Then, a novel bifunctional noble metal catalyst was prepared with the acquired hierarchical ZSM-22 zeolite as support, meanwhile the performance of catalyst in the hydrogenation isomerization of n-dodecane was evaluated. The results revealed that with a molar ratio of nTDPA/SiO₂ of 0.0170, the synthesized ZSM-22 zeolite presented proper pore structure and acidic performance, with an average crystal grain length lowered to 200 nm and an optimal distribution of acid strength and acid sites. For the n-dodecane conversion rate of 83%, the isomer selectivity increased to 68%, representing a 10-percentage-point improvement compared to the conventional blank ZSM-22 catalyst (58%). This study provides a new approach for developing highly efficient hydroisomerization catalyst through the in-situ synthesis of ZSM-22 zeolites with mesoporous structures.

The DD5 single crystal high-temperature alloy rods were massively prepared via high-speed solidification process by using a large module with dense array of seed crystals. At the same time, graphite insulation rods were appropriately inserted in between the seed crystals so that to optimize the temperature field distribution in the solidification chamber. Then, the solidification microstructure of the prepared single crystal alloys was carefully examined by means of optical microscopy, scanning electron microscopy and electron probe microanalysis, whilst the numerical simulation of the temperature field of solidification chamber was conducted as well. The results showed that, compared with the module without insulation of graphite rods, the initial dendrite spacing of the single crystal rods prepared by the modified module was reduced from 497 μm to 378 μm, and the γ/γ' eutectic phase was refined. The volume fraction of the eutectic phase decreased from 7.0% to 4.7%, the degree of segregation of elements such as W, Re, Al and Ta, and the average size of the γ' phase in the core of the dendrite and between the dendrites were reduced, and the size of the γ' phase between the core and the dendrite tended to be consistent. This indicates that the modified module can increase the temperature gradient during the high-speed solidification process and improve the uniformity of the temperature field of solidification chamber during the single crystal solidification process, which is conducive to maintaining a straight solid-liquid interface during single crystal solidification and making the solidification microstructure much uniform and dense.

In order to enhance the stability of polypropylene (PP) cables, it is essential to develop compatible PP-based semi-conductive shielding layers. In this study, semi-conductive shielding materials were prepared via melt blending using a twin-screw extruder, with PP as the matrix, OBC as the elastomer, and carbon black (CB) as the conductive filler. The effect of OBC content on the multifaceted properties of the acquired materials were investigated by observing the dispersion morphology of CB, analyzing their melting-crystallization behavior and temperature-dependent resistivity. The results showed that while increasing OBC content generally enhanced the positive temperature coefficient (PTC) effect, the prepared semi-conductive shielding material with 21% OBC (OBC21) exhibited the lowest PTC strength (I_PTC = 0.2435), with a room temperature resistivity of 24.29 Ω·cm and a maximum resistivity of 42.55 Ω·cm. Microstructural analysis demonstrates that CB is selectively dispersed within OBC, and an increase in OBC content enhances the dispersion of CB. Overall, OBC-21 exhibits the most favorable overall performance. This study provides a material design strategy for the development of high-performance PP cable shields.

A cost-effective strain-aging 2300 MPa grade medium-Mn steel (Fe-0.34C-7.4Mn-1Si-0.2V, mass fraction, %) was melted and cast. The steel was subjected to 4% pre-strain before hot rolling, then tempering at 200 ^oC for 20 min, 1 h, and 2 h respectively, after being hot-rolled. There after the evolution of volume fraction, grain size, dislocation density, and bake hardening (BH) effect of the austenite was systematically analyzed, in terms of the effect of pre-strain and annealing time on microstructure and properties of the steel. Key findings include: after pre-straining, the austenite volume fraction decreased from 31% to ~8%. Prolonged tempering coarsened austenite grains from 0.4 μm to 1 μm, while the yield strength increased from 2198 MPa to 2311 MPa, with uniform elongation stabilized at 9.1%-10.3%. A remarkable bake hardening effect was observed, with BH values rising from 460 MPa (20 min) to 573 MPa (2 h), primarily due to Cottrell atmosphere formation via carbon diffusion, which pinned dislocations. The enhanced yield strength was dominated by dislocation strengthening (pre-strain-induced) and bake hardening effect, synergistically ensuring stable performance across a wide tempering window (20 min-2 h). The low sensitivity to tempering time and broad process tolerance highlight this steel's suitability for large-scale industrial production.

Rapid electrical heating is an effective method for the efficient heat treatment of metallic materials, offering high production efficiency and process flexibility. Compared with conventional heat treatment, rapid electrical heating—driven by the synergistic effects of Joule heating and non-thermal mechanisms—can achieve rapid phase transformation and microstructural refinement within an extremely short time, while effectively suppressing grain coarsening, thereby significantly altering the kinetics of microstructural evolution. However, this process involves multiple adjustable parameters, and current industrial production largely relies on the empirical experience of operators, lacking systematic studies and theoretical support for process optimization. Herein, TC4 alloy bars were subjected to rapid electrical heating up to various heating temperatures and holding for different times, in terms of the effect of process parameters on their microstructural evolution. The results indicate that both the size and volume fraction of the β-transformed microstructure increase with the rising temperature of electrical heating and the prolonging hold time. When the holding time is short or the heating temperature is relatively low, the average grain size first decreases and then increases with increasing temperature or holding time. By longer holding times or higher heating temperatures, the grain size increases monotonically with temperature or holding time. Compared with conventional heat treatment, these microstructural evolution behaviors occur within an extremely short duration, highlighting the unique efficiency of rapid electrical heating in microstructure control. This study elucidates the characteristics and mechanisms of microstructural evolution of TC4 alloy by rapid electrical heating. The findings may provide a reference for process optimization and performance tailoring for metallic materials.

Herein, the composition of ODS MA754 alloy was recomposed by adding alloying elements such as W, Mo, Zr, and optimizing the content of Y₂O₃, then, two novel types of alloy powders with the same composition but different oxygen contents of low (M1) and high (MA4) were respectively prepared via melting-atomization method or mechanical alloying method. Next, two novel nickel-based ODS alloys, namely M1- and MA4-alloy, were prepared with these two powders as raw material, respectively, via a “hot isostatic pressing + forging + heat treatment” process. Meanwhile, the influence of the powdering techniques on the microstructure and tensile properties of the acquired alloys at different processing stages was assessed. The results showed that the MA4 alloy presents a microstructure with much uniformly dispersed nanoscale oxides like Y-Zr-Al-O and Y-Al-O compared to that of the M1 alloy. The density of the HIPed MA4 alloy is also superior to that of the M1 alloy. After forging, the second-phase particles in the MA4 alloy are finer and more evenly distributed, their role in pinning grain boundaries and inhibiting grain growth is strengthened. Solid solution treatment and solid solution + aging treatment slightly reduce the strength of the MA4 alloy but significantly increase its elongation after fracture. Compared to the M1 alloy, the strength of the MA4 alloy at all processing stages is superior. Moreover, as the solution treatment and solution treatment + aging processes are implemented, the increment in tensile and yield strength of the former is higher than the latter. The MA4 alloys acquired at the forged state, solution-treated state, and the solution + aging state, their tensile strength is 13.7%, 13.1%, and 19.9% higher, while the yield strength is 24.1%, 30.8%, and 59.0% higher, respectively, rather than those of M1 alloys. The post-fracture elongation of the MA4 alloy is lower than that of the M1 alloy to a certain extent. The MA4 alloy obtained by the solution + aging treatment stage, their post-fracture elongation was reduced to only 12.9% of the M1 alloy. Additionally, the hardness of the MA4 alloy is generally higher than that of the M1 alloy. After aging treatment, the MA4 alloy exhibits good microstructural uniformity, whereas the M1 alloy experiences abnormal grain growth, leading to microstructural inhomogeneity, which accounts for the variation in its mechanical properties. It follows that mechanical alloying is more suitable for preparing nickel-based ODS alloys.

The microstructure, elemental segregation characteristics, incipient melting temperatures of constituent phases, and homogenization mechanisms of the cast GH4065A superalloy were studied via OM, SEM with EDS, EPMA and TEM etc. Microstructural characterization reveals that the precipitation of γ+γ′ eutectics, borides, and TiN phases within γ interdendritic regions, with the newly identified η-Ni₃(Ti,Nb) and Ni₅Zr intermetallic phases were observed in the cast alloy. The phase formation sequence and the incipient melting temperatures of constituent phases was determined through metallographic analysis combined with water quenching techniques. Quantitative assessment of elemental segregation via EDS point analysis revealed that Nb, Ti, Mo, and W exhibited pronounced segregation tendencies. To address this microstructural heterogeneity, a three-stage homogenization heat treatment procedure was developed, thereby the residual segregation indices of all critical elements were all reduced below 1.2. The efficacy of this optimized thermal processing route was experimentally validated, providing crucial technical references for the industrial application of GH4065A alloy components.

Forged rods of 25 mm in diameter of a test steel accord with high carbon steel H13 were made via vacuum smelting-casting as ingot of 80 mm in diamter, then forged and spheroidizing annealed, which subjected further to solution treatment at 1030, 1040, 1050 and 1060 ^oC respectively for 30 min and then oil quenched, folllowed by tempering at 550 ^oC for 2 h and then air cooling. Herein the effect of post solution treatments on the evolution of microstructure and mechanical property, as well as the hardness and wear resistance of the high-carbon H13 test steel were investigated. The results show that the hardness of the H13 steel is mainly affected by the undissolved carbides and the carbon content in the martensite after solution treatments at 1030, 1040, 1050, 1060 ^oC, while the hardness of the tempered steel is related to the precipitation of secondary carbides from the martensite. With the increase of solution temperature, the precipitation content of secondary carbides in the steel after tempering first increases obviously and then decreases, and then increases slightly, and the maximum value is reached when the solution treatment temperature is 1040 ^oC. This is consistent with the changing trend of hardness and wear resistance of the steel after tempering. After solution treatment at 1040 ^oC, the wear loss of the H13 steel is the least of 2.61 mg, and the wear resistance is the best.