The authors review the recent advances in the development of high‐strength titanium alloys. First, they summarize conventional strengthening approaches and their mechanisms, thecorresponding ...microstructures, and the optimized mechanical properties. Subsequently, various strengthening strategies for high‐strength titanium alloys are discussed. Finally, examples of the successful development of high‐strength titanium alloys based on amorphous crystallization via solid and semi‐solid sintering are presented. The review of the interrelation between the microstructure, the strengthening, and the properties may provide significant insight into achieving novel high‐strength titanium alloys.
Development of bimodal/multimodal microstructure has attracted extensive attention in the balance of high strength and ductility of titanium alloys. This review covers the development strategies of ultrahigh strength titanium alloys consisting of nanoscale and microscale grains. Specially, a novel semi‐solid sintering technique for preparing bimodal structured titanium alloys composed of nanostructured eutectic matrix and micron‐sized precipitated phases has been proposed.
To present the pooled quantitative evidence of baseline characteristics and clinical outcomes of tocilizumab (TCZ) in patients with refractory Takayasu arteritis (TAK).
A comprehensive systematic ...review and meta-analysis was performed on all available studies retrieved from the MEDLINE, Embase, and Cochrane databases, using TCZ in patients with refractory TAK. We applied the commands
and
in Stata Software to pool overall estimates of continuous data and binomial data, respectively. A random-effects model was recruited for analysis.
Nineteen studies with 466 patients were included in this meta-analysis. The mean age at implementation of TCZ was 34.32 years. Female sex and Numano Type V were the most prominent baseline characteristics. During the 12-month follow-up when receiving TCZ treatment, pooled CRP was 1.17 mg/L (95% confidence interval CI -0.18-2.52), pooled ESR was 3.54 mm/h (95% CI 0.51-6.58), and pooled glucocorticoid dose was 6.26 mg/d (95% CI 4.24-8.27). Approximately 76% (95% CI 58-87%) of patients achieved a decrease in glucocorticoid dosage. Meanwhile, patients with TAK had a remission rate of 79% (95% CI 69-86%), a relapse rate of 17% (95% CI 5-45%), an imaging progress rate of 16% (95% CI 9-27%), and a retention rate of 68% (95% CI 50-82%). Adverse events occurred in 16% (95% CI 5-39%) of patients, and infection was the most common adverse event, with a rate of 12% (95% CI 5-28%).
TCZ treatment can provide favorable outcomes in terms of inflammatory markers, steroid-sparing effects, clinical response, drug retention and minimizing adverse effects for patients with refractory TAK.
The stretch formability behavior of an AZ61 magnesium alloy plate produced by multi-pass friction stir processing (M-FSP) was investigated, with the applied load vs. displacement curves recorded ...during Erichsen cupping tests at different punching speeds at room temperature. The stretch formability of M-FSP AZ61 magnesium alloy was significantly enhanced, compared with that of its cast counterpart. The highest Erichsen index of 3.7 mm was obtained at a punching speed of 0.1 mm/min. The improved stretch formability was mainly attributed to the grain refinement stemming from the M-FSP and the presence of extension twinning to accommodate deformation during Erichsen cupping testing.
The morphology and distribution of silicides in α/α+β type titanium alloys impress on their properties. Nevertheless, the types of silicide precipitates and their formation mechanisms remain unclear ...in β-type Ti–Nb–Zr–Ta alloys. In this study, we report the precipitation behavior of silicides formed upon aging treatment of a laser powder bed fusion (LPBF)-fabricated β-type Ti–34.5Nb–6.9Zr–4.9Ta–1.4Si (wt%, TNZTS) alloy. We further discuss their underlying formation mechanism and silicide selection-oriented mechanical properties tailoring for LPBF-fabricated TNZTS alloy. Two novel silicide precipitates were formed: a supersaturated Si–rich β–Ti matrix in the form of a network that can further transform into the (Ti, Zr)2Si (S2) phase with the increase of aging temperature; and a short, rod-like S2 precipitate adjacent to pre-existing dot-shaped S2. The former results from the aggregation of Si solute atoms towards to the dislocation walls/microbands and the subsequent precipitation reaction, while the latter arises from the considerable micro-strain around the phase boundary between the dot-shaped S2 and β-Ti owing to the large difference in their thermal expansion coefficients. The aging-treated TNZTS alloy exhibits a good combination of tensile strength (1083 ± 5 MPa) and fracture strain (5.6% ± 1.0%), which is attributed to precipitation strengthening, grain-boundary strengthening, and discontinuous intergranular silicide derived from phase selection. The obtained results provide a basis for the design and fabrication of biomedical Si-containing β-type Ti alloys with excellent mechanical properties.
Si is usually used to improve the strength and biocompatibility of β-type Ti alloys, but the types of precipitates and their formation mechanisms remain unclear. This work discusses the precipitation behavior of novel silicides formed upon aging treatment and their influence on the mechanical properties of a LPBF-fabricated β-type Ti-34.5Nb-6.9Zr-4.9Ta-1.4Si alloy. Display omitted
•Two novel silicides were formed in LPBFed TiNbZrTaSi alloy after aging treatment.•The formation mechanism of silicides was clarified during aging treatment.•The aged TiNbZrTaSi alloy exhibited a good combination of strength and plasticity.
The influence of nanocrystalline CoNiFeAl0.4Ti0.6Cr0.5 high-entropy alloy (HEA) particles addition on the microstructure and mechanical properties of SiCp/7075Al composites was investigated ...systematically. The CoNiFeAl0.4Ti0.6Cr0.5 high-entropy alloy was prepared by mechanical alloying, and the (5 vol% HEAp + 40 vol% SiCp)/7075Al (HEA-7075Al) and 45 vol% SiCp/7075Al (SiC-7075Al) composites were subsequently fabricated by squeeze casting. The HEA particles were well retained in the Al matrix and remained nanocrystalline following the squeeze casting and heat treatment process, which indicated that the CoNiFeAl0.4Ti0.6Cr0.5 high-entropy alloy has the advantage of sluggish diffusion behavior and thermal stability. The time for the HEA-7075Al composite reaching the aged-peak period (19.5 h) was slightly longer than that of the SiC-7075Al composite (15 h), indicating that the HEA particles addition has postponed the aging process, which can be ascribed to the decrease of dislocation density in the Al matrix, evaluated from XRD. Additionally, in contrast to the SiC-7075Al composite, the HEA-7075Al composite exhibits higher strength, better plasticity and higher modulus with the average values of 712 MPa, 0.82% and 171 GPa, respectively, which is the results of the good interface between HEA particles and Al matrix, high strength nanocrystalline HEA particles and proper dislocation density present in Al matrix.
A purification process to obtain coagulation factor VIII (F VIII) with high activity from human plasma was established. Based on the analysis of the size ratio between F VIII and matrix porous medium ...and its effect on the protein activity, a novel purification process designed was superporous ion exchange chromatography (IEC). The operating conditions of gigaporous and traditional anion exchange chromatography were optimized separately. The chromogenic substrate, gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were used to monitor the bioactivity and purity of the chromatographic products. The results showed that the superporous medium could not only protect structure of macro-protein but also enhance its mass transfer, finally giving FVIII product with high activity. The yield of F VIII in superporous chromatography was about five times of commercially agarose chromatography and the specific activity was up to 154 IU/mg protein. Furthermore, we studied the regeneration
Abstract
In this paper, we prepared titanium alloy through near-net forming green manufacturing, and then we quantitatively deformed the alloy and finally analyzed the deformation and fracture ...mechanism of the alloy. The result indicates that the deformation mechanism of those containing α + β lamellar structures is different from that of traditional structures. Especially, the lamellar structure can absorb the deformation energy of the alloy, thus improving the comprehensive properties of the alloy, of which the α phase mainly contributes to the plasticity of the alloy, while the β phase mainly contributes to the strength of the alloy. The two-phase combination will improve the mechanical properties of the alloy, which is completely different from the traditional strengthening mechanism of the basket structure and Widmanstatten structure.
To present the pooled quantitative evidence of basic profiles, initial treatment strategies, and clinical outcomes in patients with isolated abdominal aortic dissection (IAAD).
A comprehensive ...systematic review and meta-analysis was performed of all available studies reporting IAAD, retrieved from the MEDLINE, Embase, and Cochrane Databases. The logistic normal random effect model was fitted using the generalised linear mixed model with random intercepts to calculate the pooled proportion estimates.
Seventeen studies with 482 patients were included in this meta-analysis. Male smokers with hyperlipidaemia and hypertension were the most prominent basic profile. IAADs were predominantly spontaneous and infrarenal, and roughly half were acute and symptomatic. Approximately 67% 95% confidence interval (CI) 42–86% of patients were managed initially conservatively. In the overall population, the 30 day all cause mortality was 3% (95% CI 1–5%) and the long term mortality during follow up was 8% (95% CI 5–14%). Re-intervention during follow up occurred in 8% (95% CI 5–15%) of patients. In the subgroup analysis, patients with conservative treatment had a 30 day mortality of 1% (95% CI 0–8%), a long term mortality of 5% (95% CI 1–29%), and a re-intervention rate of 18% (95% CI 10–29%). Patients with open surgery had a 30 day mortality of 9% (95% CI 0–82%), a long term mortality of 12% (95% CI 4–31%), and a re-intervention rate of 9% (95% CI 1–44%). Patients with endovascular repair had a 30 day mortality of 2% (95% CI 0–10%), a long term mortality of 5% (95% CI 2–13%), a re-intervention rate of 6% (95% CI 3–13%), and a persistent endoleak rate of 4% (95% CI 2–10%).
Appropriate initial treatment strategies can be used to obtain acceptable clinical outcomes in patients with IAAD. Invasive intervention is necessary if patients match certain indications for intervention. Regular imaging surveillance should be provided for all patients, especially those treated conservatively.
Abstract
We present a fundamentally different approach to process the bimodal Ti-based alloy (Ti-Nb-Fe-Co-Al) by semi-solid sintering stemmed from hypoeutectic reaction, aiming at achieving ultrafine ...eutectic structure, β-Ti and micron-sized dispersed phase with strengthening effect. As expected, the microstructure of the processed Ti-Nb-Fe-Co-Al alloy contains local ultrafine eutectic structure (β-Ti and TiFe), residual equiaxed β-Ti and micron-sized dispersed phase Ti
2
Co. This alloy possesses excellent properties, the yield strength is 1620MPa and large plastic strain is 20%, superior to those of the previous fully eutectic alloy by casting. The novel idea is helpful to fabricate high-performance alloys and metals, which belonging to high temperature alloy systems.
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