Tensile Flow Behaviour and Fracture Studies of Beta Titanium Alloys at Elevated Temperatures

Tensile testing on metastable beta alloy with various microstructures was carried out in this study. Beta 21S is a metastable alloy that exhibits a wide range of material characteristics depending on the processing techniques used. Three different sheets that have been used in this paper which has the same substance but three different microstructures. At a strain rate of 0.001/s, the tensile test was done on a single sheet at five different temperatures. The sheet has developed varied microstructures, the tensile nature of the material varies the alloy’s characteristics. Mechanical characteristics for 400°C, 500°C, 600°C, and 7000°C are described for 21S sheets. The alpha phase sheet elongated at room temperature by 1-3 %, whereas the pure beta phase sheet elongated by 22-24 %. There is a significant improvement in the extension of the sheet with the variation in temperature for the alpha phase. The elongation of the pure beta phase does not alter as the temperature rises. The fracture surface was tested at all temperatures and the optimal temperature for forming the sheet has been determined

A Study on Manufacturing Technique and Alloy Characteristics of Bronze Mirrors from Jeollanam-do Region in the Three Kingdoms Period

This study analyzed the microstructures and chemical composition of three samples of bronze mirrors excavated in the Jeollanam-do region, particularly Goheung and Damyang. Under x-ray irradiation, the analysis results confirmed the broken parts and pores caused by cracks, casting, and corrosion. Major and minor elemental analysis were performed on three mirrors by Scanning electron microscopy (SEM) with Energy dispersive x-ray spectrometry (EDS) and Inductively coupled plasma mass spe ctrome try (ICP-MS). The re sult shows that the bronze mirrors containe d Cu-Sn-Pb alloys. Alpha phase and eutectic phase were observed in the microstructure, confirming that the casting was performed without additional heat treatment. Notably, Three bronze mirrors were made early Three Kingdoms period in Korea.

Atomic-Scale Investigation of the Reversible alpha to omega-Phase Lithium Ion Charge – Discharge Characteristics of Electrodeposited Vanadium Pentoxide Nanobelts

Using an electrochemical potential pulse methodology in a mixed solvent system, electrochemical deposition of amorphous vanadium pentoxide (V2O5) nanobelts is possible. Crystallisation of the material is achieved using in air annealing with the temperature of crystallisation identified using in-situ heating transmission electron microscopy (TEM). The resulting alpha-phase V2O5 nanobelts have typical thicknesses of 10-20 nm, widths and lengths in the range 5-37 nm (mean 9 nm) and 15 - 221 nm (mean 134 nm), respectively. One-cycle reversibility studies for lithium intercalation (discharge) and de-intercalation (discharge) reveal a maximum specific capacity associated with three lithium ions incorporated per unit cell, indicative of omega-Li3V2O5 formation. Aberration corrected scanning TEM confirm the formation of omega-Li3V2O5 across the entirety of a nanobelt during discharge and also the reversible formation of the alpha-V2O5 phase upon full charge. Preliminary second cycle studies reveal reformation of the omega-Li3V2O5, accompanied with a morphological change in the nanobelt dimensions. Achieving alpha-V2O5 to omega-Li3V2O5 phase reversibility is extremely challenging given the large structural rearrangements required. This phenomenon has only been seen before in a very limited number of studies also employing nanosized V2O5 materials and never before with electrodeposited nanocrystals.

An Introduction to PVDF Nanofibers Properties, and Ways to Improve Them, and Reviewing Output Enhancing Methods for PVDF Nanofibers Nanogenerators

PVDF has special piezo/pyro/ferroelectric, flexibility, low weight, biocompatibility, economical, good chemical/thermal, and high mechanical properties such as excellent nontoxic fiber/film formation. It has polar and nonpolar phases of α, β, γ, ε, and δ that the nonpolar α phase is the most stable one, but the β phase is the best of all because it has good piezo/pyro/ferroelectric properties. Copolymers are attractive because of their low weight, nontoxic, chemical acid resistance, flexibility, and ease of processing. These aspects result in their applications in many fields. They are used for piezoelectric nanogenerators, cooling/heating sensors, electronic devices (fuel cells, lithium-ion batteries (as separators), dye sensitive solar cells), filtration, oil/water separation, and photoelectric nanodevices. This review highlights the main aspects of the last decade's articles, and the focus is on the synthesis methods of PVDF nanofibers and their properties which results in their application in different fields of industry and especially focuses on finding ways to increase the output of PVDF nanofibers nanogenerators (weight/acoustic pressure nanogenerators

Piezoreflectance and Electronic Structure of Alloys of Copper with Polyvalent Solutes

<p>Piezoreflectance and other optical measurements have been made on other optical measurements have been made on a phase alloys of Cu with Zn Ga, Al, In and Ge. The samples were evaporated films deposited on the face of a resonant oscillator assembly. The application of this type of strain transducer to piezoref-reflectance alleviates systematic errors and allows the response to pure shear strains to be distinguished, even in amorphous materials, using the polarisation dependence of the results. The energies of the d band -> Fermi level threshold, the interconduction band threshold, and the L2' -> L1 critical point transition were determined for the alloys. Previous optical studies using more conventional methods either have not been able to resolve these features or have not located them with accuracy comparable with piezoreflectance. With increasing alloy concentration the d band threshold is found to shift slowly to higher energies, the inter-conduction band transitions more rapidly to lower energies. Zn impurities produced much smaller shifts than the others, indicating the importance of interactions between impurity d states and the d and conduction states of the host. Significant differences were found between the isovalent solutes Ga and A1. In concentrated alloys with Zn, Ga and Al the interconduction band threshold tended to a common value of about 2.5 eV. This lack of simple dependence on e/a, the electron per atom density in the alloy, is relevant to the understanding of the electronic structure of the Hume-Rothery alloys and the regularity of the [alpha] phase boundary.</p>

Piezoreflectance and Electronic Structure of Alloys of Copper with Polyvalent Solutes

<p>Piezoreflectance and other optical measurements have been made on other optical measurements have been made on a phase alloys of Cu with Zn Ga, Al, In and Ge. The samples were evaporated films deposited on the face of a resonant oscillator assembly. The application of this type of strain transducer to piezoref-reflectance alleviates systematic errors and allows the response to pure shear strains to be distinguished, even in amorphous materials, using the polarisation dependence of the results. The energies of the d band -> Fermi level threshold, the interconduction band threshold, and the L2' -> L1 critical point transition were determined for the alloys. Previous optical studies using more conventional methods either have not been able to resolve these features or have not located them with accuracy comparable with piezoreflectance. With increasing alloy concentration the d band threshold is found to shift slowly to higher energies, the inter-conduction band transitions more rapidly to lower energies. Zn impurities produced much smaller shifts than the others, indicating the importance of interactions between impurity d states and the d and conduction states of the host. Significant differences were found between the isovalent solutes Ga and A1. In concentrated alloys with Zn, Ga and Al the interconduction band threshold tended to a common value of about 2.5 eV. This lack of simple dependence on e/a, the electron per atom density in the alloy, is relevant to the understanding of the electronic structure of the Hume-Rothery alloys and the regularity of the [alpha] phase boundary.</p>

Assessing Fast Structure Formation Processes in Isotactic Polypropylene with a Combination of Nanofocus X-ray Diffraction and In Situ Nanocalorimetry

A combination of in situ nanocalorimetry with simultaneous nanofocus 2D Wide-Angle X-ray Scattering (WAXS) was used to study polymorphic behaviour and structure formation in a single micro-drop of isotactic polypropylene (iPP) with defined thermal history. We were able to generate, detect, and characterize a number of different iPP morphologies using our custom-built ultrafast chip-based nanocalorimetry instrument designed for use with the European Synchrotron Radiation Facility (ESRF) high intensity nanofocus X-ray beamline facility. The detected iPP morphologies included monoclinic alpha-phase crystals, mesophase, and mixed morphologies with different mesophase/crystalline compositional ratios. Monoclinic crystals formed from the mesophase became unstable at heating rates above 40 K s−1 and showed melting temperatures as low as ~30 K below those measured for iPP crystals formed by slow cooling. We also studied the real-time melt crystallization of nanogram-sized iPP samples. Our analysis revealed a mesophase nucleation time of around 1 s and the co-existence of mesophase and growing disordered crystals at high supercooling ≤ 328 K. The further increase of the iPP crystallization temperature to 338 K changed nucleation from homogeneous to heterogeneous. No mesophase was detected above 348 K. Low supercooling (≥ 378 K) led to the continuous growth of the alpha-phase crystals. In conclusion, we have, for the first time, measured the mesophase nucleation time of supercooled iPP melted under isothermal crystallization conditions using a dedicated experimental setup designed to allow simultaneous ultrafast chip-based nanocalorimetry and nanofocus X-ray diffraction analyses. We also provided experimental evidence that upon heating, the mesophase converts directly into thermodynamically stable monoclinic alpha-phase crystals via perfection and reorganization and not via partial melting. The complex phase behaviour of iPP and its dependence on both crystallization temperature and time is presented here using a time–temperature–transformation (TTT) diagram.