Development of Ultra-Fine Microstructure in Titanium via Powder Metallurgy for Improved Ductility and Strength

2008 ◽  
Vol 604-605 ◽  
pp. 223-228 ◽  
Author(s):  
Daniel Eylon ◽  
William A. Ernst ◽  
Daniel P. Kramer
Keyword(s):  
Permanent Magnets ◽  
Rapid Heating ◽  
Fine Powder ◽  
Processing Technique ◽  
Grain Structure ◽  
Fine Microstructure ◽  
Potential Applications ◽  
Grade 3 ◽  
Ti Powder ◽  
Cp Ti

In an effort to produce an ultra-fine alpha titanium equiaxed grain structure, suitable for superplastic deformation processes, Armstrong-Process CP Ti powder, was consolidated into compacts with grain-size on the order of 2 to 3 microns. This powder has very fine dendritic-shaped particles with an inherent sub-micron grain-structure. In order to preserve as much as possible the fine powder microstructural scale, the compaction was accomplished by rapid-heating and short-hold VHP, using a procedure derived from a processing technique originally developed at the University of Dayton for producing nano-phase hard permanent magnets. It was modified to suit the titanium powder, and a range of parameters was experimented to produce a variation of microstructures. One set of compaction conditions resulted in the desired microstructure, and subsequent tensile testing demonstrated strength and ductility exceeding CP Ti Grade 3, due to the ultra-fine equiaxed alpha grain structure. The paper will discuss the various microstructures and the potential applications.

Changing the magnetic properties of microstructure by directing the self-assembly of superparamagnetic nanoparticles

2015 ◽  
Vol 181 ◽  
pp. 423-435 ◽  
Author(s):  
Suvojit Ghosh ◽  
Ishwar K. Puri
Keyword(s):  
Magnetic Properties ◽  
Self Assembly ◽  
Permanent Magnets ◽  
Magnetic Moments ◽  
Residual Magnetization ◽  
Superparamagnetic Nanoparticles ◽  
Particle Interactions ◽  
Potential Applications ◽  
Empirical Generalizations ◽  
Theoretical Developments

Magnetic nanoparticles (MNPs) in a liquid dispersion can be organized through controlled self-assembly by applying an external magnetic field that regulates inter-particle interactions. Thus, micro- and nanostructures of desired morphology and superlattice geometry that show emergent magnetic properties can be fabricated. We describe how superferromagnetism, which is a specific type of emergence, can be produced. Here, superparamagnetic nanoparticles that show no individual residual magnetization are organized into structures with substantial residual magnetization that behave as miniature permanent magnets. We investigate the emergence of superferromagnetism in an idealized system consisting of two MNPs, by considering the influence that interparticle magnetostatic interactions have on the dynamics of the magnetic moments. We use this model to illustrate the design principles for self-assembly in terms of the choice of material and MNP particle size. We simulate the dynamics of the interacting magnetic moments by applying the stochastic Landau–Lifshitz–Gilbert equation to verify our principles. The findings enable a method to pattern material magnetization with submicron resolution, a useful feature that has potential applications for magnetic recording and microfluidic particle traps. The analysis also yields useful empirical generalizations that could facilitate other theoretical developments.

Spiral Friction Stir Processing (SFSP) for the Extrusion of Lightweight Alloy Tubes

2012 ◽  
Author(s):  
Fadi Abu-Farha
Keyword(s):  
Friction Stir Processing ◽  
Special Form ◽  
Bulk Material ◽  
Processing Technique ◽  
Grain Structure ◽  
The Novel ◽  
Friction Stir ◽  
Fine Grain ◽  
Processed Material ◽  
Novel Concept

While friction stir processing (FSP) has been used to refine the grain structure in sheet metals, this work explores the potentials of refining the grain structure of bulk material using the friction stirring phenomenon via the novel concept of spiral friction stir processing (SFSP). With this concept, the rotating stirring tool is plunged into the material, rather than being traversed across it as in FSP; this imposes severe plastic deformation on the material while pushing it radially outwards in complex spiral paths. By confining the material within a closed cylindrical die, the processed material is microstructurally-refined while forming a tube via a special form of SFSP called “friction stir back extrusion” (FSBE). The hypothesised concept was investigated using samples from the AA6063-T52 aluminium alloy and the AZ31B-F magnesium alloy. The preliminary results presented here demonstrate the viability of SFSP, and the special form of FSBE, in producing tubular samples that are structurally sound, with no signs of voids or internal channels. Optical microscopy was performed at key locations within selected tube specimens, and the obtained micrographs clearly show the presence of a stir zone with a fine grain structure; grain size measurements demonstrate the effectiveness of the processing technique in refining the microstructure of the starting material.

scholarly journals Development of the freeze–thaw processing technique for disaggregation of indurated mudrocks and enhanced recovery of calcareous microfossils

2014 ◽  
Vol 33 (2) ◽  
pp. 193-203 ◽  
Author(s):  
Alice E. Kennedy ◽  
Angela L. Coe
Keyword(s):  
Hydrogen Peroxide ◽  
Extraction Method ◽  
Enhanced Recovery ◽  
Rapid Heating ◽  
Low Cost ◽  
Processing Technique ◽  
Freeze Thaw ◽  
Calcareous Microfossils ◽  
Processing Techniques ◽  
Further Development

Abstract. Microfossil extraction from indurated mudrocks is widely acknowledged as challenging, especially for foraminifera. Here we report development of the freeze–thaw extraction method through the addition of rapid heating, detergent and ultrasound stages. We use indurated mudrock samples from the Toarcian (Early Jurassic) of Yorkshire, UK to assess the effectiveness and develop the freeze–thaw method. We compare our results from freeze–thaw with those from standard foraminifera processing techniques, including the use of hydrogen peroxide. Processing by freeze–thaw increased the degree of mudrock disaggregation and resulted in no damage or dissolution of foraminifera. Following the freeze–thaw method with treatment in white spirit and sodium hexametaphosphate aided the separation of foraminifera from the disaggregated clays and was twice as efficient as pressure washing. Samples processed with hydrogen peroxide contained damaged microfossils and an under representation of delicate calcareous foraminifera. Many other studies of indurated mudrocks have used hydrogen peroxide to extract foraminifera, and this might have resulted in apparently barren intervals. The freeze–thaw method outlined here provides a low-cost, low-risk and successful method of disaggregating and extracting calcareous microfossils from indurated mudrocks. We anticipate our method may be relevant for other fossil groups and merits further development.

scholarly journals Base Plate Preheating Effect on Microstructure of 316L Stainless Steel Single Track Deposition by Directed Energy Deposition

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5129
Author(s):  
Abhilash Kiran ◽  
Martina Koukolíková ◽  
Jaroslav Vavřík ◽  
Miroslav Urbánek ◽  
Jan Džugan
Keyword(s):  
Process Parameters ◽  
Significant Influence ◽  
Rapid Heating ◽  
Grain Morphology ◽  
Base Plate ◽  
High Energy ◽  
Grain Structure ◽  
Single Track ◽  
Boundary Misorientation ◽  
Electron Backscattered Diffraction

The microstructural morphology in additive manufacturing (AM) has a significant influence on the building structure. High-energy concentric heat source scanning leads to rapid heating and cooling during material deposition. This results in a unique microstructure. The size and morphology of the microstructure have a strong directionality, which depends on laser power, scanning rate, melt pool fluid dynamics, and material thermal properties, etc. The grain structure significantly affects its resistance to solidification cracking and mechanical properties. Microstructure control is challenging for AM considering multiple process parameters. A preheating base plate has a significant influence on residual stress, defect-free AM structure, and it also minimizes thermal mismatch during the deposition. In the present work, a simple single track deposition experiment was designed to analyze base plate preheating on microstructure. The microstructural evolution at different preheating temperatures was studied in detail, keeping process parameters constant. The base plate was heated uniformly from an external heating source and set the stable desired temperature on the surface of the base plate before deposition. A single track was deposited on the base plate at room temperature and preheating temperatures of 200 °C, 300 °C, 400 °C, and 500 °C. Subsequently, the resulting microstructural morphologies were analyzed and compared. The microstructure was evaluated using electron backscattered diffraction (EBSD) imaging in the transverse and longitudinal sections. An increase in grain size area fraction was observed as the preheating temperature increased. Base plate preheating did not show influence on grain boundary misorientation. An increase in the deposition depth was noticed for higher base plate preheating temperatures. The results were convincing that grain morphology and columnar grain orientation can be tailored by base plate preheating.

Effects of various sintering methods on microstructure and mechanical properties of CP-Ti powder consolidations

2014 ◽  
Vol 24 ◽  
pp. s59-s67 ◽  
Author(s):  
Je-ha SHON ◽  
Jong-moon PARK ◽  
Kyeong-sik CHO ◽  
Jae-keun HONG ◽  
Nho-kwang PARK ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Microstructure And Mechanical Properties ◽  
Ti Powder ◽  
Cp Ti

scholarly journals Anisotropic Growth and Magnetic Properties of α″-Fe16N2@C Nanocones

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 890
Author(s):  
Yong Li ◽  
Qifeng Kuang ◽  
Xiaoling Men ◽  
Shenggang Wang ◽  
Da Li ◽  
...  
Keyword(s):  
Permanent Magnets ◽  
High Coercivity ◽  
Anisotropic Growth ◽  
Easy Magnetization ◽  
One Pot ◽  
Magnetization Direction ◽  
Air Atmosphere ◽  
Potential Applications ◽  
Carbon Coated ◽  
Oxidation In Air

α″-Fe16N2 nanomaterials with a shape anisotropy for high coercivity performance are of interest in potential applications such as rare-earth-free permanent magnets, which are difficult to synthesize in situ anisotropic growth. Here, we develop a new and facile one-pot microemulsion method with Fe(CO)5 as the iron source and tetraethylenepentamine (TEPA) as the N/C source at low synthesis temperatures to fabricate carbon-coated tetragonal α″-Fe16N2 nanocones. Magnetocrystalline anisotropy energy is suggested as the driving force for the anisotropic growth of α″-Fe16N2@C nanocones because the easy magnetization direction of tetragonal α″-Fe16N2 nanocrystals is along the c axis. The α″-Fe16N2@C nanocones agglomerate to form a fan-like microstructure, in which the thin ends of nanocones direct to its center, due to the magnetostatic energy. The lengths of α″-Fe16N2@C nanocones are ~200 nm and the diameters vary from ~10 nm on one end to ~40 nm on the other end. Carbon shells with a thickness of 2–3 nm protect α″-Fe16N2 nanocones from oxidation in air atmosphere. The α″-Fe16N2@C nanocones synthesized at 433 K show a room-temperature saturation magnetization of 82.6 emu/g and a coercive force of 320 Oe.

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