Superplastic Forming and Reaction Diffusion Bonding Process of Hollow Structural Component for Mg-Gd-Y-Zn-Zr Rare Earth Magnesium Alloy

This work fabricated a double hollow structural component of Mg-8.3Gd-2.9Y-0.8Zn-0.2Zr alloy by superplastic forming (SPF) and reaction-diffusion bonding (RDB). The superplastic characteristic and mechanical properties of Mg-8.3Gd-2.9Y-0.8Zn-0.2Zr alloy sheets at 250–450 °C were studied. Tensile tests showed that the maximum elongation of tensile specimens was about 1276.3% at 400 °C under a strain rate of 1 × 10−3 s−1. Besides, the effect of bonding temperature and interface roughness on microstructure and mechanical properties of the reaction diffusion-bonded joints with a Cu interlayer was investigated. With the increase of temperature, the diffusion coefficient of Cu increases, and the diffusion transition region becomes wider, leading to tightening bonding of the joint. However, the bonding quality of the joint will deteriorate due to grain size growth at higher temperatures. Shear tests showed that the highest strength of the joints was 152 MPa (joint efficiency = 98.7%), which was performed at 460 °C.

Comparison of Chitosan Characterization from Mussel Shell Waste Using Varying Concentration of Solvents

Massive amounts of mussel shell waste are generated and wasted from the aquaculture processing sectors, resulting in environmental pollution. This material contains chitosan as a valuable compound characterized as a non-toxic structural component with several food processing applications or medicinal applications. In this research, mussel shells were processed using different solvents concentrations in several stages: demineralization, deproteination, decolourization, and deacetylation. Our result showed that the C2 samples gained a high degree of deacetylation (31.8±0.21%) with low moisture and ash content and medium weight of yield. Further research is recommended to purify chitosan using various instrumentation and assess its bioactivity.

Structure of Alloys for (Sm,Zr)(Co,Cu,Fe)z Permanent Magnets: III. Matrix and Phases of the High-Coercivity State

Observations of the surface domain structure (Kerr-effect), optical metallography, scanning electron microscopy (SEM-SE), and electron microprobe analysis (EPMA-SEM), measurements of major and minor magnetic hysteretic loops were used to study pseudo-single-crystal samples of (Sm,Zr)(Co,Cu,Fe)z alloys subjected to heat treatments to the high-coercivity state, which are used in fabricating sintered permanent magnets. Correlations between the chemical composition, hysteretic properties, structural components, domain structure, and phase state were determined for the concentration ranges that ensure wide variations of 4f-/4d-/3d-element ratio in the studied samples. The phase state formed by collinear and coherent phase components determines the high coercive force and ultimate magnetic hysteresis loops of the pseudo-single crystals. It was found that the 1:5 phase with the hexagonal structure (P6/mmm) is the matrix of the alloys for (Sm,Zr)(Co,Cu,Fe)z permanent magnets; the matrix undergoes phase transformations in the course of all heat treatments for the high-coercivity state. The heterogeneity observed with optical magnifications, namely, the observation of main structural components A and B, is due to the alternation, within the common matrix, of regions with modulated quasi-spherical precipitates and regions with hexagonal bipyramids (cellular phase) although, traditionally, many investigators consider the cellular phase as the matrix. It is shown that the relationship of volume fractions of structural components A and B that account for more than 0.9 volume fraction of the total, which is due to the integral chemical composition of the alloys, determines the main hysteretic performances of the samples. The Zr-rich phases, such as 5:19, 2:7, and 6:23, and a structural component with the variable stoichiometry (Sm(Co,Cu,Fe)3.5–5) that is almost free of Zr and contains up to 33 at% Cu, were found only within structural component A in quantities sufficient for EPMA analysis.

More Than Just a Spearhead: Diverse Functions of PAAR for Assembly and Delivery of Toxins of the Contractile Injection Systems

The type VI secretion system (T6SS) belongs to the evolutionarily related group of contractile injection systems that employ a contractile outer sheath to inject a rigid spear-like inner tube into target bacterial and eukaryotic cells. The tip of the rigid tube is often decorated by a PAAR-repeat protein as a key structural component.

THE UPDATED STRUCTURE OF THE INNOVATIVE POTENTIAL OF THE REGION

The article analyzes the main problems hin-dering Russia's transition to an innovative economy. The fundamental indicators of in-novative development are highlighted, the main of which is the innovative potential of the region. The analysis of the existing struc-tures of the innovative potential of the region is carried out by considering each structural component identified by various domestic authors over the past twenty years. The need to create an updated structure of the innovative potential of the region is due to the high variability of the theoretical base of the object under study, which has a negative impact on the development of methods for its assessment. Based on current global economic and innovative trends, an updated structure has been finalized, which includes strategically necessary components that fully reflect the versatility and multicomponence of this indicator.

Development of near homogeneous properties in wire arc additive manufacturing process for near-net shaped structural component of low-carbon steel

Low-carbon steel is a common structural material, but additively manufactured structural component of this material is rare due to its inhomogeneous properties. In this article, the wire arc additive manufacturing method was used to achieve near homogeneous properties of a low-carbon steel structural component. The process heat input was optimised for the desired layer geometry, and then the optimal energy was applied with a time delay to deposit individual layers. The time delay was used to achieve cyclic heating and cooling treatment of deposited layers. The best possible robotic tool path movement with multi point arcing was further adopted in the study to achieve proper thermal distribution across the structural component. The microstructure of layers was dominated by quasi-polygonal ferrite morphology and pearlite precipitation, with little variation in quantity across the component. The hardness profile was almost consistent with the average hardness of ∼176.92 HV. The proof stress slightly increases with decrease in grain size and increase in ferrite/pearlite ratio, however, the overall tensile behaviour is homogeneous with average σ0.2, σu and ε% values of 427.78 MPa, 527.89 MPa and 22.31%, respectively. The quasi-ductile fracture was generally occurred due to void coalescence around larger inclusions. The overall analysis showed that more than 90% of homogeneity was achieved in microstructural and mechanical behaviour of the deposited component.