Experimental study on severe plastic deformation of Ti by novel equal-channel angular pressing

This study involves experimental investigation on severe plastic deformation (SPD) of Ti using novel equal-channel angular pressing (ECAP) at ambient temperature. Ti wire is tightly encapsulated in a hollow host material made of Al-based functionally graded material (FGM). The host material is prepared by embedding Al–Al3Ti alloy into Al. Three types of the Al–Al3Ti alloys with different Al3Ti volume fractions are used to prepare the host materials. ECAP for specimens is carried out for up to eight passes by route A. The microstructure and hardness of ECAPed specimens are investigated. The changes in microstructure and the increase in the hardness value of Ti with increased number of ECAP passes are evidences showing that Ti is successfully deformed by this technique

Formation of compositional gradient in Al/SiC FGMs fabricated under huge centrifugal forces using solid-particle and mixed-powder methods

Formations of graded distribution of SiC ceramic particles within the hollow cylindrical shaped Al/SiC functionally graded materials (FGMs) fabricated by centrifugal solid-particle method (CSPM) and centrifugal mixedpowder method (CMPM) under huge centrifugal force are experimentally and theoretically investigated. The movement of SiC ceramic particles in viscous liquid under centrifugal force is explained based on Stoke's law. The effect of compositional gradient of particles on viscosity is taken into account. Also, the effect of temperature distribution on viscosity and density are considered. A computer code to simulate the formation of compositional gradient in the Al/SiC FGMs fabricated by CSPM and CMPM is developed. From the results, it is found that the volume fraction of SiC ceramic particles can be graded from the inner to the outer surface of hollow cylindrical shaped Al/SiC FGMs by CSPM. Meanwhile by CMPM, the SiC ceramic particles can be dispersed on the outer surface of hollow cylindrical shaped Al/SiC FGMs. The graded distribution in Al/SiC FGMs under huge centrifugal force is found to be significantly affected by the mold temperature but less affected by the temperature of molten Al and casting atmosphere

New Processing Routes for Functionally Graded Materials and Structures through Combinations of Powder Metallurgy and Casting

New processing routes for metal-matrix functionally graded materials (FGMs) and structures through combinations of powder metallurgy and casting are described in this chapter. Centrifugal mixed-powder method is introduced as a processing method for metal-matrix FGMs at first. The centrifugal mixed-powder method is a developed technique of centrifugal casting by setting predesigned mixed powder in a spinning mold in advance. As an example of processed FGMs by this method in our previous studies, Cu-based FGMs with dispersed diamond particles are shown. Graded structures in the Cu-based FGMs are investigated through scanning electron microscope (SEM) observations of microstructures. As the latest processing method for metal-matrix FGMs developed by our research group, centrifugal sintered-casting method is shown. The centrifugal sintered-casting method is a modified processing technique of the centrifugal mixed-powder method. In the centrifugal sintered-casting method, FGMs are processed by the combination of centrifugal sintering and centrifugal casting. Al–Si alloy and Cu-based FGMs with dispersed diamond particles are introduced as examples. Applications of metal-matrix FGMs processed by the centrifugal sintered-casting method are also described. Fabricated metal-matrix FGMs can be used as grinding wheel and applied to carbon fiber-reinforced plastic (CFRP) machining

Finite element analysis of severe plastic deformation of difficult-to-work material by equal-channel angular pressing at ambient temperature

An alternative technique of the equal-channel angular pressing (ECAP) process for difficult-to-work materials at ambient temperature is proposed by embedding a difficult-to-work material into an easy-to-work material. The easy-to-work material as a host material assists the deformation of the difficult-to-work material. The ECAP process is simulated by the finite element method (FEM). For this study, Ti as the difficult-to-work material is embedded into an Al-based functionally graded material (FGM) matrix. FEM is conducted with Ti embedded into a different host material type as well as a different die channel geometry. The strain distribution of the specimen after a single ECAP pass is analyzed. From the obtained results, it is found that the strain distribution in Ti is strongly influenced by the host material and the shape of the die channe

Secreted Phospholipase PLA2G2D Contributes to Metabolic Health by Mobilizing ω3 Polyunsaturated Fatty Acids in WAT

Polyunsaturated fatty acids (PUFAs) confer health benefits by preventing inflammation and obesity and by increasing thermogenesis in brown and beige adipocytes. As well as being supplied exogenously as nutrients, PUFAs are largely stored in membrane glycerophospholipids and released by phospholipase A2s (PLA2s). However, the molecular identity of the PLA2 subtype(s) that supplies endogenous PUFAs for metabolic homeostasis remains unclear. Here we show that PLA2G2D, a secreted PLA2 isoform, is constitutively expressed in M2-type macrophages in white adipose tissue (WAT) and shows a reciprocal correlation with obesity. Studies using global and macrophage-specific Pla2g2d-deficient mice reveal that PLA2G2D increases energy expenditure and thermogenesis by facilitating adipocyte browning, thereby ameliorating diet-induced obesity, insulin resistance, and WAT inflammation. Mechanistically, PLA2G2D constitutively supplies a pool of PUFAs, ω3 in particular, in WAT. Thus, our present findings underscore the contribution of the macrophage-driven PLA2G2D-ω3 PUFA axis to metabolic health

Temperature and solvent dependence of stiffness of poly{n-hexyl-[(s)-3-methylpentyl]silylene} in dilute solutions

Terao K., Terao Y., Teramoto A., et al. Temperature and solvent dependence of stiffness of poly{n-hexyl-[(s)-3-methylpentyl]silylene} in dilute solutions. Macromolecules, 34(13), 4519-4525, May 25, 2001. Copyright © 2001, American Chemical Society. https://doi.org/10.1021/ma010212w

Conformational transitions in poly{n-hexyl-[(S)-3-methylpentyl]silylene) in dilute solution: Temperature and molecular weight dependence detected by circular dichroism

Terao K., Terao Y., Teramoto A., et al. Conformational transitions in poly{n-hexyl-[(S)-3-methylpentyl]silylene) in dilute solution: Temperature and molecular weight dependence detected by circular dichroism. Macromolecules, 34(18), 6519-6525, July 24, 2001. Copyright © 2001, American Chemical Society. https://doi.org/10.1021/ma0104433

Stiffness of polysilylenes depending remarkably on a subtle difference in chiral side chain structure: Poly{n-hexyl-[(S)-2-methylbutyl]silylene)} and poly{n-hexyl-[(S)-3-methylpentyl]silylene}

Terao K., Terao Y., Teramoto A., et al. Stiffness of polysilylenes depending remarkably on a subtle difference in chiral side chain structure: Poly{n-hexyl-[(S)-2-methylbutyl]silylene)} and poly{n-hexyl-[(S)-3-methylpentyl]silylene}. Macromolecules, 34(8), 2682-2685, March 16, 2001. Copyright © 2001, American Chemical Society. https://doi.org/10.1021/ma002030s