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Hafnia‐based ceramic coating is considered one of the candidates to substitute yttria partially stabilized zirconia material as thermal barrier coating working above 1200°C. In this work, a series of TiO2‐doped HfO2 ceramics (Hf1–xTixO2, x = 0%, 5%, 10%, 15%, 20%, and 40%) were fabricated by solid‐state reaction. The microstructure, fracture toughness, and thermal conductivity were systematically investigated. The results show that Hf1–xTixO2 ceramics are comprised of monoclinic HfO2 and orthorhombic HfTiO4 phases when Ti4+ doping amount is between 5% and 20%, and the weight fraction of HfTiO4 phase linearly increases with the Ti4+ content and finally reaches 100% for Hf0.6Ti0.4O2. The fracture toughness of TiO2‐doped HfO2 ceramic is higher than 1.75 MPa m.5 when TiO2 content is no more than 15% and decreases below 1.5 MPa m0.5 if TiO2 content further increases. The thermal conductivity is significantly decreased by TiO2 doping attributed to the precipitated HfTiO4 phase. Considering the mechanical properties and thermal insulation capacity, the doping of 15% TiO2 would be beneficial for the HfO2‐based ceramics. [ABSTRACT FROM AUTHOR]

The effect of enzymatic dephosphorylation, using intestinal alkaline phosphatase, on the structure of casein micelles in caprine micellar casein concentrate (MCC) was studied. An optimal condition, involving preheating the MCC dispersion, pH 6.4, 2.5 mg casein/mL and 0.4 U phosphatase/mL, was established and used to prepare MCC with 0–49% dephosphorylation by incubation at 37 °C for 0–180 min. β-Casein showed marked dephosphorylation and formed multi-phosphorylated isoforms depending on dephosphorylation degree, whereas α s - and κ-caseins showed limited and fast dephosphorylation, respectively. With increasing dephosphorylation, both the colloidal calcium and the calcium sensitive micellar caseins, especially β-casein, were gradually dissociated, and the calcium insensitive serum κ-casein was gradually associated with the micelles. The dissociated β-casein fraction was predominated by isoforms with lower number of phosphate groups. For micelles with increasing dephosphorylation, the molar mass decreased, the gyration and hydrodynamic radii decreased, the ratio of gyration to hydrodynamic radii and micellar hydration increased, the spherical morphology was generally retained, and the internal protein inhomogeneity disappeared progressively. These results suggest that after dephosphorylation, the caprine micelle framework underwent an intra-micellar mass redistribution, and become more loose and homogeneous. [Display omitted] • Caprine MCC incubated with phosphatase for 0–3 h reached 0–49% dephosphorylation. • β- and κ-Caseins were preferably dephosphorylated over α s -casein. • Micellar calcium and β-casein were dissociated with increasing dephosphorylation. • Dissociated β-casein was predominated by isoforms with less phosphate group. • M w decreased and R g /R h increased for micelles with increasing dephosphorylation. [ABSTRACT FROM AUTHOR]

Optimizing and regulating the process parameters to form a uniform distribution of nanosized dispersoids remains a major challenge in additive manufacturing oxide dispersion strengthened (ODS) alloys. This study introduces the influence of scanning speed and laser power on the microstructure evolution of laser powder bed fusion (LPBF) ODS FeCrAl alloy. Low laser power and high scanning speed reduce the size of oxide particles and increase their number density. The energy density threshold is 83 J/m3, below which the powder fails to achieve complete melting, leading to the formation of defects during solidification. High density and large number of oxide particles were obtained for the printed samples under the parameters of 140 W laser power and 600 mm/s scanning speed. The average size and number density of oxide particles were ∼ 21.61 nm and ∼ 1.8 × 1020/m3, respectively. High scanning speed have a rapid cooling rate which affects the dislocation density and the average width of the columnar grains. Low laser power significantly weakens the 〈100〉 fiber texture, which is related to the degree of recrystallization in the remelted region. The core-shell oxides consisting of Y-Al-O and Y-Ti-O were distributed in the samples deposited at low and high laser powers, respectively. The formation of core-shell oxide particles in LPBF ODS FeCrAl alloys involves solid-state amorphization and recrystallization. This study can be a guideline to achieve materials with specific microstructure for ODS alloys. • High-density ODS FeCrAl alloys were built by selective laser melting (SLM) process. • Low laser power and high scanning speed result in obtaining small-sized and high-density nanoparticles. • The modification of the laser power affects the composition of core-shell structured oxide particles. • The formation of nanoparticles in SLM ODS FeCrAl alloys involves solid-state amorphization and recrystallization. [ABSTRACT FROM AUTHOR]

Powder bed fusion (PBF) is a well-established method in the additive manufacturing (AM) industry. Despite its popularity, effectively managing the microstructure and mechanical properties of PBF-produced components remains a significant engineering challenge. This study aims to address this challenge by investigating the thermal accumulation effect of PBF substrate preheating on sample microstructure. The study demonstrates the graded microstructure resulting from "in-situ aging" at 630 °C at different deposition heights. The results reveal how heat accumulation and cooling rate contribute to the varying α p lamellae content and α phase selection across different regions. Notably, the bottom region, with an α p lamellae content of 53.5% and a βr content of 46.5%, exhibits the highest of fracture toughness value of 87.5 MPa.m1/2. The mechanical properties exhibit a clear grade distribution with increasing deposition height. In-situ manipulation of microstructure and mechanical properties provides theoretical and engineering guidance for future AM strategies. [ABSTRACT FROM AUTHOR]

The metal additive manufacturing (AM) technology offers a unique advantage for production of complex and unconventional parts. However, the thermal history during the AM process often leads to anisotropy in the mechanical properties and inherent porosity of the deposits, which limits their performance compared to traditional forgings. To overcome these limitations, laser powder bed fusion (LPBF) technology was employed to produce single-step die-forging preforms. This innovative approach used coarse powder with a wide distribution of particle sizes to create a variety of molten pool structures, preventing the growth of columnar β grains in AM Ti–5Al–5V–5Mo–3Cr–1Zr (Ti-55531) alloys. The subsequent die-forging process eliminated inherent defects and regulated grains to be near-equiaxed, significantly improving the mechanical properties and reducing anisotropy. With proper post-heat treatment, the strength-ductility trade-off of the Ti-55531 alloy was adjusted to meet standards. This unconventional process route produced parts with isotropic and excellent mechanical properties, overcoming the defects and anisotropic properties of AM parts. This supplement to the traditional manufacturing process of high-performance titanium alloy parts holds great promise for future applications. [ABSTRACT FROM AUTHOR]

• RAFM steel with high strength and excellent ductility was successfully fabricated by SLM. • The SLMed RAFM have significantly superior mechanical properties to wrought specimens. • The coexistence of nano and micron grains results in superior performance of SLMed specimens. Reduction activated ferrite/martensitic (RAFM) steel has been identified as the most promising structural material for future fusion reactors due to its properties such as low activation and high thermal conductivity. However, the complex internal water cooling tubing increases the difficulty of conventional processing. Herein, RAFM steel with high strength and excellent ductility was successfully fabricated by selective laser melting (SLM) technology. Compared with wrought materials, the SLM-fabricated specimens exhibit significant superiority in mechanical properties. Furthermore, the strength is prominently enhanced in the horizontal direction, with almost no loss of ductility. However, the strength gain in the vertical direction is at the expense of ductility. This work provides a potential method for the preparation of structural materials for nuclear fusion. [ABSTRACT FROM AUTHOR]

Nano‑potassium bubble strengthened tungsten (W-K) alloy with excellent overall performance has been proven to be one of the most desirable plasma facing materials (PFMs). However, some key properties, e.g., thermal heat resistance, ductile-brittle transition temperature (DBTT), strength and toughness need to be further improved to meet the requirements of fusion reactor. Herein, pure yttrium (Y) was doped in W-K alloy to achieve multiple strengthening effects. The grains of W-K alloy have been significantly refined, and the tensile strength was improved along with the introducing of Y. Thermal shock cracking threshold has increased to exceed 0.62 GW/m2. Interestingly, the existing form and size of the precipitates differed with the change of doping amount, leading to the nonlinear evolution of DBTT. The W-K alloy with 0.1 wt%-Y doping content (W-K-0.1Y) showed the best match of strength and toughness. Furthermore, coupled with relatively good thermal conductivity, W-K-0.1Y alloy displayed prominent thermal shock resistance. This work may pave a way for designing PFMs with higher performance. • Pure yttrium (Y) was doped in W-K alloy to realize multiple strengthening effects. • The grains of W-K alloy were significantly refined by Y doping. • The existing form of the precipitates differed with the change of doping content. • The DBTT of W-K-0.1Y alloy has been reduced to ~200 °C. • The thermal shock cracking threshold of W-K-0.1Y alloy exceeded 0.62 GW/m2. [ABSTRACT FROM AUTHOR]

The layer-wise additive manufacturing process offers a unique approach to achieve a novel graded microstructure which can fulfill the conflicting requirement of contradictory properties. The present study investigated microstructure evolution and mechanical properties of a near β alloy Ti–5Al–5Mo–5V–3Cr–1Zr fabricated by additive manufacturing using electron beam melting. In combination, the high preheating temperature in electron beam melting, the low β transus (850 °C) in Ti–5Al–5Mo–5V–3Cr–1Zr, and the increasingly accumulated heat with build height resulted in an in-situ formed graded hierarchical microstructure from an α+β lamellar microstructure at the specimen bottom to an α p +α s bi-lamellar microstructure at the specimen top. Such a gradually changing microstructure was obtained by the same electron beam melting parameter set, and its formation was related to the controlled secondary α precipitation through manipulating the stability of metastable β-phase at different specimen heights. The resultant hardening effect in the bi-lamellar microstructure was attributed to the precipitation of fine secondary α. [ABSTRACT FROM AUTHOR]