Rare-earth elements (REE)-added Ti alloys have competitive advantages owing to improved machinability, but the effects of REE on environmental durability have rarely been reported. In this study, we investigated effects of REE additions of 0.2, 0.8, and 2.0 wt% cerium (Ce) and neodymium (Nd) in Ti on the microstructure, corrosion, high-temperature oxidation, and wear resistance. Microstructural analysis confirmed the formation of CeO2 and Nd2O3 precipitates, whose morphology and number density varied with the REE content. Such CeO2 and Nd2O3 precipitates affected corrosion resistance, high-temperature resistance, hardness and wear resistance. Due to the addition of REE in Ti, the oxidation state of Ti in surface oxide layer was changed, so that the corrosion resistance of Ti–Ce and Ti–Nd alloys were decreased with the increase of REE concentrations. Lower concentrations (0.2 and 0.8 wt%) of REE addition in Ti contributed to precipitation hardening, thus the hardness and wear resistance increased compared to commercially pure titanium (CP–Ti), which is the base metal of REE-added Ti alloys. However, the coarsened CeO2 and Nd2O3 precipitates with 2.0 wt% of Ce and Nd resulted in lower hardness and wear resistance than CP-Ti. Low concentration of REE (0.2 and 0.8 wt %) enhanced a high-temperature oxidation resistance due to formation of compact initial oxide scale on surface. At the same REE concentration, Ti–Ce alloys showed better corrosion resistance, hardness, wear resistance and high-temperature oxidation resistance than Ti–Nd alloys.

Anisotropic shrinkage during sintering remains a challenge in architectured porous ceramics, yet its mechanistic origin and controllability are not fully understood. Here, the evolution of anisotropic shrinkage in freeze-cast Al2O3 is quantitatively analyzed using high-resolution in-situ dilatometry combined with microstructural characterization. A clear directional transition is observed during heating: shrinkage is initially dominated by the perpendicular direction at low temperatures, but reverses to the parallel direction above ∼1396 °C, resulting in a final anisotropy of ∼1.44%. This behavior is consistent with the competition between grain-boundary and lattice diffusion, indicating that anisotropic shrinkage depends on the dominant densification mechanism rather than on structural anisotropy alone. By linking curvature-driven capillarity (γ/r) to direction-dependent mass transport pathways, a mechanistic framework is proposed to explain the emergence of shrinkage anisotropy. Based on this framework, two-step sintering (TSS) is employed to promote grain-boundary diffusion while suppressing lattice diffusion, leading to a near-complete elimination of anisotropic shrinkage (∼0.2%) without sacrificing densification. These findings suggest that shrinkage anisotropy can be effectively regulated through diffusion-pathway control and provide useful guidance for designing sintering strategies to achieve dimensional stability in porous materials.

This study investigates the reduction behavior and effect of refractories applied to reduction furnaces during hydrogen reduction steelmaking. Refractories composed of mullite and/or andalusite were heat treated for 72 h at 1100 °C in a 100

This study investigates the influence of initial crystallographic texture on the deformation mechanisms during three-point bending of AZ31 Mg alloy sheets. Three distinct orientations are examined by using the following bending specimens: (i) the normal direction (ND) sample, where the c-axes are predominantly aligned along the specimen thickness, (ii) the rolling direction (RD) sample, where the c-axes are mostly aligned along the longitudinal direction, and (iii) the 45 sample, where the c-axes are tilted at approximately 45° from both the thickness and longitudinal directions. The bending properties vary significantly depending on the initial texture, thereby affecting the strain accommodation and dominant deformation modes. The ND sample exhibits the lowest bendability due to its unfavorable orientation for {10–12} extension twinning and basal slip, which results in poor strain accommodation and early crack initiation in the outer tensile side. By comparison, the RD sample demonstrates an approximately 22.1% improvement, with extensive {10–12} extension twinning in the outer tensile zone. Meanwhile, the 45 sample exhibits the highest bendability (approximately 75.7% greater than that of the ND sample) due to sustained activation of both basal slip and {10–12} extension twinning, promoting uniform strain distribution and delaying fracture. Detailed electron backscatter diffraction analysis reveals that the 45 sample retains favorable crystallographic orientations for basal slip throughout bending, minimizing strain localization and enhancing the bendability. These findings highlight the importance of tailoring the initial texture in order to optimize the bending properties of Mg alloy sheets, and provide valuable insights for improving the manufacturability of Mg-based structural components.

This work investigated the effect of cerium (Ce) addition on the wear behavior of commercially pure titanium (CP-Ti) by varying the Ce content to 0.8, 1.4, and 2.0 wt.%. Alloys were fabricated using plasma arc melting, and wear resistance was evaluated under loads of 1 N and 5 N dry sliding condition. Microstructural characterization confirmed the formation of CeO2 precipitates, whose size and distribution varied with the Ce content. The Ti-0.8Ce alloy exhibited the highest hardness (203 HV), showing a 35% increase compared to CP-Ti, and the lowest wear rate reduced by approximately 47% and 22% under 1 N and 5 N loads, respectively. In contrast, Ti-1.4Ce and Ti-2.0Ce formed coarse CeO2 precipitates, which acted as third-body abrasives. Although these alloys showed lower average friction coefficients than CP-Ti (up to 22% reduction), the enhanced abrasive interaction promoted material removal and increased wear rates. Notably, Ti-2.0Ce exhibited the most severe degradation in wear resistance, with wear rates increases of 21% and 27% under 1 N and 5 N loads, respectively. These findings demonstrate that while CeO2 precipitates reduce friction by suppressing direct metal–metal contact, their abrasive nature adversely affects wear resistance when the particle size and volume fraction are excessive. Therefore, 0.8 wt.% Ce was identified as the optimal composition for improving the wear resistance, achieving the best combination of high hardness, low wear rate without excessive third-body abrasion.

To realize direct reduction by hydrogen in iron and steel making industry, hydrogen resistance of refractory bricks should be sufficient. However, the effects of hydrogen on refractory bricks have not been studied intensively. In this study, the physical and chemical changes in mullite‐based refractory bricks were investigated for use in a hydrogen atmosphere. After exposure to hydrogen at 1100°C for 72 h, the mechanical strength was reduced by up to ∼ 15%, with a change in color. Multi‐aspect analysis indicated possible causes: the reduction of SiO 2 , that is, SiO(g) formation, for the strength degradation, and the reduction of Fe 2 O 3 and/or TiO 2 for the optical changes. Both were identified from defects at the interface of the mullite particles observed using scanning electron microscopy and the lower‐valence states detected via X‐ray photoelectron spectroscopy. In addition, thermodynamic analysis revealed that the dominant reduction mechanism of the oxides was direct reduction due to the hydrogen reaction rather than indirect reduction due to low oxygen partial pressure.

A coupled lattice Boltzmann-cellular automata simulation method was developed to investigate the effects of electron beam heat sources on melt pool dynamics and process parameters on the microstructure of Ti-6Al-4V alloy during electron beam cold hearth melting (EBCHM) process. Temperature distribution and fluid flow behaviours within the melt pool were analysed, with findings indicating that an optimized beam power distribution leads to a more uniform temperature and stable melt pool profile, mitigating the risks of excessive melt vaporization. The simulation results reveal the influence of casting speed on melt pool depth, temperature gradients, and the columnar-to-equiaxed transition. The results indicate that higher casting speeds promote shallower melt pools and reduce temperature gradients, enhancing equiaxed grain nucleation and promoting more isotropic microstructures. This approach supports the effective control of microstructure and composition uniformity in EBCHM-produced ingots.

This study investigates the influence of bending speed on the springback and thinning behavior of pure titanium sheets, with a particular focus on microstructural evolution during bending. To evaluate these effects, V-bending tests were performed at bending speeds of 1, 10, and 100 mm/min, which approximately correspond to strain rates of 1.3 x 10-4, 1.3 x 10-3, and 1.3 x 10- 2 s- 1, respectively. The results reveal that increased bending speed leads to greater springback. During bending, plastic deformation initiates from both the inner and outer surfaces of the sheet and gradually penetrates toward the mid-thickness. However, this penetration is increasingly suppressed as the bending speed rises, resulting in the formation of a thick, deformation-free middle zone. This undeformed middle zone enhances elastic recovery and intensifies springback. On the other hand, faster bending promotes more uniform thickness reduction across the sheet, thereby mitigating localized thinning. These findings highlight a trade-off between minimizing springback and achieving uniform thickness, underscoring the complexity of simultaneously optimizing both parameters in the forming of pure titanium sheets. This study offers valuable insights for improving the precision and efficiency of titanium sheet forming processes.

For the successful application of porous Al2O3, mechanical strength is essential for both functionality and durability. Sufficient mechanical strength can be achieved by controlling densification and grain growth during the sintering process, resulting in a higher ratio of density to grain size. To accomplish this, two different strategies were combined: two-step sintering (TSS) and MgO doping. A beneficial TSS condition was deduced from the activation energy relationship between densification (63.48 kJ/mol) and grain growth (806.11 kJ/mol). Consequently, a higher relative density (45.44 % TD) with a smaller grain size (0.814 mu m) was obtained compared to the case without TSS. These steps also led to higher compressive strength (9.37 MPa). In addition, the doping effect was confirmed through comparisons with samples without MgO doping. These results demonstrate the synergetic effect of the TSS technique and MgO doping, highlighting the comprehensive strategy proposed here for enhanced mechanical stability.

In this study, we investigated the peculiar flow behavior during the isothermal deformation of a novel TiAl composition at 1200 °C and 1300 °C under high strain rate conditions using Gleeble® Thermal-Mechanical Simulators. The initial yield-point phenomenon, resembling strain hardening at both temperatures, is attributed to the remnant lamellar microstructure. Secondary hardening at 1200 ℃ is caused by dislocation accumulation at the grain boundaries of the α phase, without the formation of dynamically recrystallized γ lamellar grains. In-grain misorientation axes analysis revealed a shift in the dominant deformation slip mode of the α phase from the prismatic slip system to a combined prismatic and basal slip system. The disappearance of γ lamellar laths after the first strain hardening and during secondary hardening is likely initiated by a deformation-induced γ→α phase transition within the γ phase matrix by the extended dislocation with intrinsic stacking faults and occurred simultaneously in the whole γ lamellae.

Heterogeneous deformation occurs between grains in polycrystalline alpha-titanium. Understanding the role of temperature in local deformation is essential for its applications in extreme environments such as cryo- or high-temperature, but the underlying mechanism still remains elusive. Here we report a study of grain-scale deformation behaviour in CP-Ti plate at the temperature range from -60 degrees C to 280 degrees C. The full-field strain measurements were conducted on the tensile samples loaded parallel (RD) and transverse (TD) to the rolling direction, using in-situ optical microscopy and digital image correlation (OM-DIC). The DIC local strain maps were coupled with scanning electron microscopy and electron backscatter diffraction analysis. The grain boundary sliding and slip transfer occurred depending on the geometric relationship (i.e., deformation compatibility) between adjacent grains at 20 degrees C, and a micro-crack was observed at the {10 (1) over bar1} twist boundary. The strain was recovered in the grains in the RD sample favourable for slip, whilst more accumulated in the grains in TD sample unfavourable for slip at 280 degrees C. The plasticity of grains differs with decreasing temperature to -40 degrees C, resulting in the presence of soft/hard grain pairs. The strong strain localisation between the soft and hard grains led to the cracking along the GBs (RD) and cross the grains (TD). Interestingly, the cracking was significantly reduced with decreasing temperature to -60 degrees C due probably to the temperature dependence of the plasticity of grains. The strain-hardening behaviour of alpha-Ti polycrystals was significantly affected by the temperature and crystal orientation dependence of grain-scale deformation mechanism.

To increase mechanical strength of porous ceramics, here, an effective two-step sintering (TSS) technique capable of producing highly porous alumina with enhanced mechanical strength is suggested. Based on the sintering theories, here, a significantly lower activation energy for densification at low temperature region allowed a beneficial temperature range for the TSS to be deduced. With a specific TSS regime (T1 = 1550 & DEG;C and T2 = 1400 & DEG;C), significantly higher compressive strength levels (8.00-15.24 MPa) were measured with an apparent porosity of 56.49% compared to conventional sintering (1.03-1.86 MPa) with similar apparent porosity of 57.84%. Specifically, another TSS regime (T1 = 1550 & DEG;C and T2 = 1380 & DEG;C) left submicron-sized open pores within the lamellar walls, providing a hierarchical porous structure with enhanced mechanical strength. An evaluation of the mechanical stability by a finite element analysis indicated outstanding compressive strength even with small pores in the lamella walls.

This study demonstrates that the addition of the rare earth element Erbium (Er) significantly enhances the machinability and tensile properties of titanium (Ti). Pure Ti alloys and Er-added Ti alloys with 0.5-1.1 wt.% Er content were prepared, and their microstructure, machinability, and tensile properties were compared. Two different types of Er secondary phase particles were identified in the microstructure: pure Er and Er-oxide. The amounts of these particles increased with higher Er content. The machinability of the Eradded Ti alloys was significantly improved due to the ability of Er secondary particles to cut machining chips or absorb heat from localized deformation within the Ti matrix. In addition, Er-added Ti alloys exhibited higher strength than pure Ti. The strength enhancement was attributed to grain refinement induced by the Er element. Er secondary phase particles reduced the β grain size during solidification, and they also served as preferential sites for α nucleation during the β → α phase transformation, resulting in a refined microstructure. In addition, the Er secondary phase contributed to the strength enhancement through the well-known precipitation strengthening mechanism. Although ductility decreased with higher Er content due to the increased amount of Er secondary phase particles, 0.5 wt.% Er-added Ti showed no such degradation; its ductility was comparable to that of pure Ti. Er-oxidation was expected to reduce oxygen content within the Ti matrix, enhancing intrinsic Ti ductility; this effect offset the adverse impact on ductility caused by the Er secondary phase particles. Above 0.5 wt.% Er, the adverse effects caused by the Er secondary phase particles overwhelmed the beneficial effect caused by the reduction in oxygen content. The present findings will contribute significantly to the development of highly machinable Ti alloys with superior tensile properties.

Freeze-cast ceramics provide a wide range of applications, including filters, catalyst supports, heat-resistant materials, and biomaterials. The unique porous structure of freeze-cast ceramics offers new perspectives in various fields. However, for the functionality and durability of freeze-cast ceramics, a sufficient mechanical strength of the porous architecture is essential. In the freeze-casting process, the final microstructure is determined during sintering at high temperature through densification and grain growth, highlighting the importance of sintering techniques, which can be originated from sintering strategies in the bulk system. In other words, enhancing densification while suppressing grain growth should be realized by tailoring processing variables and/or materials variables. In this review, we suggest an effective way to control the microstructure by addition of dopants in porous alumina prepared by freeze-casting. The results provide a facile method for microstructure control and provide insight into the selection of promising dopants for better mechanical strength of porous ceramics.

This paper considers the beta/alpha transformation of Ti–6Al–4V alloy using a lattice Boltzmann method (LBM) – cellular automata (CA) coupled method in terms of microstructural evolution during phase transformation. Particularly, the effects of the cooling rate on microstructures such as beta grain size, alpha colony size, and alpha lath thickness were examined as well as the overall morphologies. The LBM and CA were used to implement the diffusion of alloy components and phase transformation, respectively. Additionally, the thermodynamic and kinetic data for simulating the ternary alloy system were obtained from CALPHAD software to utilize the equilibrium phase diagram calculations. The initial states of the beta grain and its composition fields affect the processing of beta/alpha phase transformation and the final alpha + beta phase morphologies. Validation of the proposed method was conducted to compare the simulation results with experimental trends for microstructures of Ti–6Al–4V from the literature. The error in prediction of microstructural morphologies were 20% in the average alpha thickness with deviation of up to 5 μm.

This study investigated the effects of electropulsing treatment (EPT) condition on the microstructure and microhardness of cold-rolled Grade 2 Ti sheet. Particular attention was paid to the dependence of the material properties on the electric current direction, referred to as electropulsing anisotropy. Direct-current (DC) EPT was applied along either the rolling direction (RD) or transverse direction (TD) of the rolled sheet. EPT along the TD resulted in a higher heating rate and maximum temperature, whereas that along the RD accelerated the static recrystallization (SRX) process under identical electropulsing parameters. Such a discrepancy was interpreted using the elongated grain structure and basal texture in the cold-rolled Ti sheet. These results were further supported by microhardness measurements, confirming the presence of electropulsing anisotropy during DC EPT in Ti alloys for the first time. In addition, the employed EPT was compared to a traditional furnace heat treatment (FHT) with rigorous temperature and time control, wherein the optimum EPT process spent only 13% of the processing time to complete SRX with a lower thermal energy requirement. This indicates a significant athermal contribution of EPT to electropulsing anisotropy.

The sheet formability of cold-rolled pure titanium (Ti) was remarkably recovered after being slightly rolled at 77 K, i.e., subjected to cryogenic-deformation treatment (CDT). This recovery occurred because CDT increased the thinning capability of the cold-rolled pure Ti, thereby suppressing cracking by restraining local strain concentration during subsequent sheet forming. The thinning capability was high because CDT formed twins, and slip in their orientations was favorable to accommodate thinning deformation. In addition, twinning during deformation contributed to high thinning capability. The twinning was possible because during deformation, the preformed twins by CDT acted as twin nuclei, enabling growth-dominant twinning without requiring a substantial activation stress for twin nucleation. CDT also increased the strength of cold-rolled pure Ti by twinning-induced grain refinement and dislocation accumulation. These abilities of CDT are noteworthy because sheet formability and strength are typically mutually exclusive. Thus, CDT achieved a superior combination of sheet formability and strength, which cannot be achieved by cold rolling alone, overcoming the trade-off between these two properties in pure Ti.

This research demonstrates that single-shot laser shock peening followed by annealing significantly improves the strength−ductility balance of the AZ31 alloy. This is achieved by creating a heterostructure that reduces the dislocation density and enhances work hardening, thereby presenting a viable method for developing magnesium alloys with superior mechanical properties.

This work investigated the effect of rolling temperature (25-800 degrees C) on rolling-texture development and sheet formability of pure Ti. The rolling temperature significantly affected the development of the typical transverse-direction (TD)-split basal texture in pure Ti sheet by altering the tilting angle of (0001) basal poles. Notably, a normal-direction (ND) basal texture, where the tilting angle of (0001) basal poles was approximately 0 degrees, developed at an intermediate rolling temperature of 400 degrees C. This result is remarkable because the ND basal texture is rare in pure Ti. Formation of this unusual ND basal texture was attributed to significant activation of basal slip. In contrast, a typical TD-split basal texture was dominant at the other rolling temperatures. Formation of this typical texture was attributed to pyramidal slip. After subsequent recrystallization annealing, sheet formability was examined. Despite their different textures, the sheets previously rolled at the different rolling temperatures showed similar formability. This similarity occurred because any given texture could not simultaneously provide in-plane stretching uniformity and thinning capability during sheet forming. The present study suggests an important guidance for modifying texture of pure Ti sheets to effectively increase their formability.

Addition of similar to 3 wt% Ce to cast pure Ti induced formation of numerous fine Ce particles on the microstructure. The Ce-alloyed cast Ti had both high tensile strength and ductility, which are unattainable simultaneously in cast pure Ti. The mechanisms by which the Ce particles increased tensile properties were identified.