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Brazing characteristics of a Zr(Ti)-Cu(Fe)-Al glassy alloy was investigated using a Zircaloy-4 alloy as a base metal. A low melting temperature (solidus: 840 °C, liquidus: 880 °C) of the brazing alloy was obtained at the near-eutectic composition of Zr55Ti5Cu25Fe5Al10 (at.%) designed by a partial replacement of Zr by Ti, and Cu by Fe from a well-known Zr60Cu30Al10 ternary alloy. This quinary brazing alloy exhibited excellent melting and wetting characteristics and good compatibility with the base metal. At brazing temperatures below the liquidus of the brazing alloy, the joint consisted of a relatively fine dendritic structure (α-Zr + Zr2Cu) with a massive segregation of Zr2Cu in the central zone by a eutectic solidification of the molten brazing alloy during a cooling stage, whereas a homogeneous joint was obtained at 890 °C with a predominant formation of acicular α-Zr phases holding an intercellular lamellar mixture (α-Zr + Zr2Cu), which was produced by an isothermal solidification during a brazing holding time. The mechanical properties of the joints were strongly dependent on a degree of joint homogeneity, and the bonding strength of the joints was high enough to cause a fracture in the Zircaloy-4 base metal, when the central segregation of massive Zr2Cu was completely eliminated at the brazing temperature of 890 °C. [ABSTRACT FROM AUTHOR]

Brazing characteristics of a Zr(Ti)–Cu(Fe)–Al glassy alloy was investigated using a Zircaloy-4 alloy as a base metal. A low melting temperature (solidus: 840 °C, liquidus: 880 °C) of the brazing alloy was obtained at the near-eutectic composition of Zr 55 Ti 5 Cu 25 Fe 5 Al 10 (at.%) designed by a partial replacement of Zr by Ti, and Cu by Fe from a well-known Zr 60 Cu 30 Al 10 ternary alloy. This quinary brazing alloy exhibited excellent melting and wetting characteristics and good compatibility with the base metal. At brazing temperatures below the liquidus of the brazing alloy, the joint consisted of a relatively fine dendritic structure ( α -Zr + Zr 2 Cu) with a massive segregation of Zr 2 Cu in the central zone by a eutectic solidification of the molten brazing alloy during a cooling stage, whereas a homogeneous joint was obtained at 890 °C with a predominant formation of acicular α -Zr phases holding an intercellular lamellar mixture ( α -Zr + Zr 2 Cu), which was produced by an isothermal solidification during a brazing holding time. The mechanical properties of the joints were strongly dependent on a degree of joint homogeneity, and the bonding strength of the joints was high enough to cause a fracture in the Zircaloy-4 base metal, when the central segregation of massive Zr 2 Cu was completely eliminated at the brazing temperature of 890 °C. [ABSTRACT FROM AUTHOR]

A Zr–Ti–Cu–Fe quaternary eutectic alloy was employed as a new Be-free brazing filler metal for Zircaloy-4 to supersede physically vapor-deposited Be coatings used conventionally with several disadvantages. The quaternary eutectic composition of Zr58Ti16Cu10Fe16 (at.%) showing a low melting temperature range from 832°C to 853°C was designed by a partial substitution of Zr with Ti based on a Zr–Cu–Fe ternary eutectic system. By applying an alloy ribbon with the determined composition, a highly reliable joint was obtained with a homogeneous formation of predominantly grown α-Zr phases owing to a complete isothermal solidification, exhibiting strength higher than that of Zircaloy-4. The homogenization of the joint was rate-controlled by the diffusion of the filler elements (Ti, Cu, and Fe) into the Zircaloy-4 base metal, and the detrimental segregation of the Zr2Fe phase in the central zone was completely eliminated by an isothermal holding at a brazing temperature of 920°C for 10min. [ABSTRACT FROM AUTHOR]

The article discusses a study that examined the possible application of the zirconium-titanium-nickel-copper-beyllium (Zr-Ti-Ni-Cu-Be) amorphous alloy as a filler for the low temperature brazing between dissimilar Ti and stainless steels (STS). Two major problems in Ti-STS are described. Changes made to the microstructure of the Ti-STS dissimilar joints brazed with the Zr-Ti-Ni-Cu-Be amorphous filler for the increased brazing temperature are also explained.

Abstract: Microstructural evolution of the Ti–Cu dissimilar joints brazed by a Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 (at.%) amorphous alloy filler was investigated at a temperature of 820°C for 1–20min. As the brazing time increased, the overall composition of the joint sensitively changed from Ti-rich to Cu-rich owing to the different reactivity of the Zr in the filler with the Ti and Cu in the base metals. Based on such time-dependent compositional change, the formation of the intermetallic phases in the joint was basically divided into three stages; Stage (1): formation of interfacial Ti2Cu, Stage (2): formation of two-phase structure with Ti2Cu/TuCu and Cu2TiZr, and Stage (3): transformation to Cu-rich phases. At Stage (2), the joint was fully produced isothermally by directional phase transformations with fine dendritic and columnar two-phase structures, revealing the highest bonding strength due to its controlled intermetallic morphology. [Copyright &y& Elsevier]

Abstract: Titanium (Ti) was successfully brazed at low temperatures below 800°C by employing a Zr41.2Ti13.8Ni10.0Cu12.5Be22.5 (at.%) bulk metallic glass (BMG) alloy as a filler. Through the use of this alloy filler, the detrimental segregation of Zr–Cu–Ni filler elements was completely eliminated by heating to well below 800°C, so the resultant joint was quite homogeneous with a coarse acicular structure. The disappearance of the Zr–Cu–Ni segregated region was rate-controlled by the diffusion of the filler elements in the Ti base metal. Remarkably, the mechanical property and corrosion resistance of the homogeneous joint brazed at 800°C for 10min were mostly comparable to those of bulk Ti. [Copyright &y& Elsevier]

Abstract: Strong bonding between titanium (Ti) and stainless steel (STS) was achieved by employing a commercially available Ag–28Cu (wt.%) filler, and more importantly with a help of an Ag interlayer. A mass transport of the Ti elements from the substrate into the molten filler was completely prevented through the use of the Ag interlayer, so the resultant brazed joint was free from any brittle Ti-based intermetallic compounds. Notably, this Ti–STS dissimilar joint displayed a remarkable improvement in its bonding strength, demonstrating the potential application of an Ag interlayer for joining Ti and its alloys to various structural steels. [Copyright &y& Elsevier]

Abstract: The fracture property improvement of Zr-based bulk amorphous alloy containing ductile crystalline particles was explained by directly observing microfracture processes using an in situ loading stage installed inside a scanning electron microscope (SEM) chamber. Strength and apparent fracture toughness measured from the in situ fracture test of the amorphous alloy containing crystalline particles were lower than those of the monolithic amorphous alloy, whereas its ductility was higher. According to the microfracture observation, shear bands were initiated from ductile crystalline particles, and the propagation of the shear bands or cracks was blocked by crystalline particles, thereby resulting in stable crack growth which could be confirmed by the fracture resistance curve (R-curve) behavior. This increase in fracture resistance with increasing crack length improved fracture properties of the alloy containing crystalline particles, and could be explained by mechanisms of blocking of crack or shear band propagation, formation of multiple shear bands, crack blunting, and shear band branching. [Copyright &y& Elsevier]

Abstract: In this study, effects of various crystalline particles formed in strip-cast Zr-base amorphous matrix composites on deformation behavior were investigated. The compressive and fracture toughness test results indicated that the ductility of the strip-cast alloys containing hard/brittle crystalline particles as well as containing ductile β-phase particles was higher than that of the monolithic amorphous alloy. From finite element calculations and in situ microfracture observations, this ductility improvement could be explained by the role of the particles to initiate shear bands and to block the shear band propagation. However, this improvement could be obtained only when the size and volume fraction of crystalline particles and characteristics of amorphous matrix were optimized by controlling the strip casting conditions. [Copyright &y& Elsevier]

Abstract: Twin-roll strip casting was utilized to fabricate the sheet products of Zr- and Cu-base bulk amorphous alloys with quite different glass forming abilities (GFAs). Simulation of the solidification behavior of the these amorphous forming alloys during twin-roll strip casting shows that suitable cooling rate can be achieved by twin-roll strip casting to form amorphous structure through the thickness of sheet. Optimum twin-roll strip casting conditions have been suggested based on the simulation results. Actual twin-roll strip casting shows that both Zr-base alloy with high GFA and Cu-base alloy with much less GFA can be strip cast forming amorphous structure. The results indicate that the twin-roll strip casting is a viable process for continuous fabrication of sheets of bulk amorphous alloys with a wide range of critical cooling rates. [Copyright &y& Elsevier]

Abstract: Twin-roll strip casting has been utilized to fabricate the sheet products of bulk amorphous alloys. Simulation of solidification behavior and actual twin-roll strip casting show that the optimum casting conditions are such that the alloy is in supercooled liquid state at roll nip area rather than fully amorphized. [Copyright &y& Elsevier]

Abstract: Effects of crystalline phase particles formed in a strip-cast Zr-base bulk amorphous alloy on strength, ductility, and fracture toughness were investigated by directly observing microfracture processes using an in situ loading stage installed inside a scanning electron microscope chamber. The compressive and fracture toughness test results indicated that strength, ductility, and fracture toughness of the strip-cast amorphous alloy were higher than those of the as-cast monolithic amorphous alloy, although the strip-cast alloy contained a considerable amount (4.5vol.%) of hard, brittle crystalline particles. According to the in situ microfracture observation, crystalline particles were easily cracked under low stress levels, acted as blocking sites of shear band or crack propagation, and provided initiation sites of multiple shear bands. Thus, the improvement of mechanical properties in the strip-cast alloy could be explained by mechanisms of (1) blocking of crack propagation, (2) formation of multiple shear bands, and (3) crack deflection by crystalline particles. [Copyright &y& Elsevier]

Effects of crystalline particles formed in the strip cast Zr-base bulk metallic glass (BMG) alloy on ductility and strength were investigated in this study by directly observing microfracture processes. The compressive and fracture toughness test results indicated that ductility, strength, and fracture toughness of the strip cast BMG alloy were higher than those of the die cast monolithic BMG alloy, although the strip cast alloy contained a considerable amount (4.5 vol.%) of hard, brittle crystalline particles. The improvement of mechanical properties in the strip cast BMG alloy could be plausibly explained by mechanisms of (1) blocking of shear bands or crack propagation, (2) formation of multiple shear bands, and (3) crack deflection by crystalline particles. [Copyright &y& Elsevier]

Abstract: Magnetic pulsed compaction (MPC) was introduced to consolidate mixed diamond and cobalt (Co) granule powders for the production of drilling segments. The diamond-Co samples prepared by MPC at the compacting pressure of 4GPa showed a high sintered density of 99.6% as well as a high green density of 86.4%. A fine and homogeneous microstructure and a high hardness were also observed in the sintered bulk. Finally, a perforating test revealed that a higher drilling speed of 11.71cm/min and a longer tool life of 7.96m were obtained for the drilling segments prepared by the MPC process, whereas the values for those fabricated by a conventional process were 10.15cm/min and 6.55m, respectively. This property improvement of the MPCed segments was attributed basically to the enhanced green density and the homogeneous distribution of the diamonds. [Copyright &y& Elsevier]

Cognitive deficits are a core feature across psychiatric disorders. Emerging evidence indicates that metabolic pathways are highly relevant for the substrates and phenomenology of the cognitive domain. Herein, we aimed to determine the effects of liraglutide, a GLP−1R agonist, on brain structural/volumetric parameters in adults with a mood disorder. This is the secondary analysis of a 4-week, pilot, proof-of-concept, open-label study. Participants ( N =19) exhibiting impairments in executive function with either major depressive disorder (MDD) or bipolar disorder (BD) were recruited. Liraglutide 1.8 mg/day was added as an adjunct to existing pharmacotherapy. Structural magnetic resonance imaging (MRI) scanning was obtained at baseline and endpoint. Results showed that at endpoint there was significant weight loss (mean: 3.15%; p <0.001). Changes in frontal and striatal volumes were significantly correlated with changes in body mass index (BMI), indicating the weight loss was associated with volume increase in most regions (e.g. r =−0.561, p =0.042 in the left superior frontal area). After adjusting for intracranial volume, age, gender, and BMI, we observed significant changes from baseline to endpoint in multiple regions (e.g. RR: 1.011, p =0.049 in the left rostral middle frontal area). Changes in regional volumes were associated with improvement in executive function (e.g. r =0.698, p =0.003 for the right superior frontal area). Adjunctive liraglutide results in clinically significant weight loss, with corresponding improvement in cognitive function; changes in cognitive function were partially moderated by changes in brain morphometry, underscoring the interrelationship between weight and brain structure/function. [ABSTRACT FROM AUTHOR]

Background: There is a paucity of treatments that are capable of reliably and robustly improving cognitive function in adults with mood disorders. Glucagon-like peptide-1 is synthesized centrally and its receptors are abundantly expressed in neural circuits subserving cognitive function. We aimed to determine the effects of liraglutide, a GLP-1 receptor (GLP-1R) agonist, on objective measures of cognition in adults with a depressive or bipolar disorder.Methods: In this 4-week, pilot, open-label, domain-based study (e.g. cognition), we recruited 19 individuals with major depressive disorder (MDD) or bipolar disorder (BD) and an impairment in executive function, defined as a below-average performance in the Trail Making Test-B (TMTB). Liraglutide 1.8mg/day was added as an adjunct to existing pharmacotherapy.Results: Participants had significant increases from baseline to week 4 in the TMTB standard score (age and education corrected) (Cohen's d=0.64, p=0.009) and in a composite Z-score comprising multiple cognitive tests (i.e. Digit Symbol Substitution Test, Rey Auditory Verbal Learning Test, Stroop test) (Cohen's d=0.77, p<0.001). Neither changes in mood rating scales nor metabolic parameters were associated with changes in cognitive performance (all p>0.05); however baseline insulin resistance (IR) and body mass index (BMI) moderated the changes in the composite Z-score (p=0.021 and p=0.046, respectively), indicating larger responses in individuals with higher IR and BMI at baseline. There was a significant increase in lipase (p<0.001), but individual values were above the upper limit of normality.Limitations: Small sample size, open-label design, lack of a placebo group.Conclusions: Liraglutide was safe and well tolerated by a sample of non-diabetic individuals with mood disorders and had beneficial effects on objective measures of cognitive function. Larger studies with controlled trial designs are necessary to confirm and expand the results described herein. [ABSTRACT FROM AUTHOR]