Processing of Titanium and its Alloys by Microwave Energy

2014 ◽  
Vol 1019 ◽  
pp. 11-18 ◽  
Author(s):  
M. Ashraf Imam ◽  
Jerry Feng ◽  
Benjamin Y. Rock ◽  
Arne W. Fliflet
Keyword(s):  
Microwave Sintering ◽  
Superplastic Forming ◽  
Cost Effective ◽  
Grain Structure ◽  
Cycle Times ◽  
Fine Grain ◽  
Microwave System ◽  
Conventional Sintering ◽  
Direct Alloying ◽  
Rapid Processing

Microwave sintering of titanium and its alloys is a recent development in powder metallurgy of titanium. The sintering in an atmospheric pressure argon gas environment or vacuum is potentially cost effective and energy efficient compared to conventional sintering methods due to the possibility of direct microwave heating of the titanium powder via in-depth energy deposition augmented by hybrid heating in a ceramic casket. The in-depth heating permits very rapid processing (cycle times of potentially less than 10 minutes) which is intended to preserve a very fine grain structure in the final product resulting in excellent mechanical properties and the possibility of superplastic forming. We are investigating this approach using an S–Band microwave system. The process can be also used for composites, laminates, direct alloying, and functionally gradient materials. Evaluations to optimize different parameters for controlling the final density, microstructure, and properties of these materials are underway and results are discussed.

Microwave Sintering and Melting of Titanium Powder for Low-Cost Processing

2010 ◽  
Vol 436 ◽  
pp. 131-140 ◽  
Author(s):  
Ralph W. Bruce ◽  
Arne W. Fliflet ◽  
Hugo E. Huey ◽  
Chad Stephenson ◽  
M. Ashraf Imam
Keyword(s):  
Titanium Powder ◽  
Low Cost ◽  
Microwave Sintering ◽  
High Vacuum ◽  
Cost Effective ◽  
Naval Research ◽  
Energy Usage ◽  
Electrode Consumption ◽  
Microwave System ◽  
Direct Induction

The emerging reduction technologies for titanium from ore produce powder instead of sponge. Conventional methods for sintering and melting of titanium powder are costly, as they are energy intensive and require high vacuum, 10-6 Torr or better, since titanium acts as a getter for oxygen at high temperature, adversely affecting mechanical properties. Other melting processes such as plasma arcs have the additional problem of electrode consumption, and direct induction heating of the titanium powder is problematic. Microwave sintering or melting in an atmospheric pressure argon gas environment is potentially cost effective and energy efficient due to the possibility of direct microwave heating of the titanium powder augmented by hybrid heating in a ceramic casket. We are investigating this approach at the Naval Research Laboratory using an S–Band microwave system. The experimental setup and the results of melting and sintering experiments will be described including a rough estimate of energy usage.

scholarly journals Mechanism-based constitutive equations for superplastic forming of TA15 with equiaxed fine grain structure

2017 ◽  
Vol 207 ◽  
pp. 1874-1879 ◽  
Author(s):  
L. Zhao ◽  
T. Yasmeen ◽  
P. Gao ◽  
S. Wei ◽  
Z. Bai ◽  
...  
Keyword(s):  
Constitutive Equations ◽  
Superplastic Forming ◽  
Grain Structure ◽  
Fine Grain

Conventional and microwave sintering studies of SrTiO3

1995 ◽  
Vol 10 (8) ◽  
pp. 2052-2059 ◽  
Author(s):  
Horng-Yi Chang ◽  
Kuo-Shung Liu ◽  
I-Nan Lin
Keyword(s):  
Mixed Oxide ◽  
Anatase Phase ◽  
Microwave Sintering ◽  
Sintering Behavior ◽  
Chemical Route ◽  
Highly Active ◽  
Oxide Powders ◽  
Fine Grain ◽  
Conventional Sintering ◽  
Higher Temperature

Using the nonconventional sintering technique, such as microwave sintering, it is observed to enhance the densification rate of SrTiO3 materials as effectively as employing the highly active powders prepared by the chemical route. Although the chemically derived powders demonstrate better sinterability than the mixed oxide powders, the thermal analysis indicates that the segregation of Ti4+-containing clusters during decomposition of precursors in the direct pyrolysis (DP) process induces the occurrence of TiO2 particles (anatase phase) prior to the formation of SrTiO3 phase. These particles retard the necking process required to sinter the materials. The spray pyrolysis (SP) process can circumvent the preferential nucleation of TiO2 phase and, therefore, produce powders exhibiting superior sintering behavior to the DP-derived powders. The microwave sintering technique, on the other hand, substantially enhances the rate of diffusion of the ions in the materials such that even the mixed oxide powders can be sintered at a temperature about 200 °C lower than that needed to achieve the same density in a conventional sintering process. Fine grain (∼4 μm) microstructure is obtained for the materials microwave sintered at 1220 °C for 10 min. The migration of grain boundaries requires higher temperature to initiate than the formation of neckings between the grains. The grain growth occurs only when the material was sintered at temperatures higher than 1250 °C.

Microstructure Development in a High Current Density NbTi Superconducting Composite

1985 ◽  
Vol 43 ◽  
pp. 186-189
Author(s):  
P. J. Lee ◽  
D. C. Larbalestier
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Cold Drawing ◽  
Heat Treatments ◽  
Grain Structure ◽  
Fine Grain ◽  
Boundary Film ◽  
Quantitative Basis ◽  
Cold Worked ◽  
Very High

Several features of the metallurgy of superconducting composites of Nb-Ti in a Cu matrix are of interest. The cold drawing strains are generally of order 8-10, producing a very fine grain structure of diameter 30-50 nm. Heat treatments of as little as 3 hours at 300 C (∼ 0.27 TM) produce a thin (1-3 nm) Ti-rich grain boundary film, the precipitate later growing out at triple points to 50-100 nm dia. Further plastic deformation of these larger a-Ti precipitates by strains of 3-4 produces an elongated ribbon morphology (of order 3 x 50 nm in transverse section) and it is the thickness and separation of these precipitates which are believed to control the superconducting properties. The present paper describes initial attempts to put our understanding of the metallurgy of these heavily cold-worked composites on a quantitative basis. The composite studied was fabricated in our own laboratory, using six intermediate heat treatments. This process enabled very high critical current density (Jc) values to be obtained. Samples were cut from the composite at many processing stages and a report of the structure of a number of these samples is made here.

CONTINUOUS-CAST 45-12 DUCTILE IRON

Alloy Digest ◽  
1989 ◽  
Vol 38 (4) ◽  
Keyword(s):  
Continuous Casting ◽  
Ductile Iron ◽  
Heat Treating ◽  
Grain Structure ◽  
Continuous Cast ◽  
Good Surface ◽  
Fine Grain ◽  
High Speeds ◽  
Good Surface Finish ◽  
Iron Grade

Abstract Ductile Iron grade 45-12 produced by continuous casting has consistent density and fine grain structure. It is the softest of the regular grades of ductile iron and it machines at high speeds with good surface finish. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, and tensile properties. It also includes information on heat treating, machining, and joining. Filing Code: CI-58. Producer or source: Federal Bronze Products Inc..

KETOS

Alloy Digest ◽  
1960 ◽  
Vol 9 (8) ◽  
Keyword(s):  
Physical Properties ◽  
Tensile Properties ◽  
Tool Steel ◽  
Heat Treating ◽  
Grain Structure ◽  
Steel Company ◽  
Fine Grain ◽  
Crucible Steel

Abstract KETOS is an oil-hardening non-deforming tool steel having deep hardening qualities with a fine grain structure. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as deformation. It also includes information on forming, heat treating, and machining. Filing Code: TS-96. Producer or source: Crucible Steel Company of America.

Ionic Conductivities of Doped CeO2 Thin Films as Related to Their Microstructure

1995 ◽  
Vol 411 ◽  
Author(s):  
Chunyan Tian ◽  
Siu-Wai Chan
Keyword(s):  
Thin Films ◽  
Electrical Properties ◽  
Ionic Conductivities ◽  
Dielectric Constants ◽  
Grain Structure ◽  
X Ray Diffraction ◽  
Fine Grain ◽  
Brick Layer Model ◽  
Columnar Grain ◽  
Beam Deposition

ABSTRACTThin films of 4% Y2O3 doped CeO2/Pd film/(001)LaA103 with a very low pinhole density were successfully prepared using electron-beam deposition technique. The microstructure of the films was characterized by x-ray diffraction and the electrical properties were studied as a function of temperature with AC impedance spectroscopy. A brick layer model was adopted to correlate the electrical properties to the microstructure of the films, which can be simplified as either a series or a parallel equivalent circuit associated with either a fine grain or a columnar grain structure, respectively. The conductivities of the films fell between the conductivities derived from the two circuit models, suggesting that the films are of a mixed fine grain and columnar grain structure. The measured dielectric constants of the films were found smaller than that of the bulk.

Magnetic properties of MnZn ferrite with ultra-fine grain structure

2003 ◽  
Vol 254-255 ◽  
pp. 538-540 ◽  
Author(s):  
J Moulin ◽  
Y Champion ◽  
J.M Grenèche ◽  
F Mazaleyrat
Keyword(s):  
Magnetic Properties ◽  
Grain Structure ◽  
Mnzn Ferrite ◽  
Fine Grain

The Possibility of Manufacturing Long-Length Metal Products with Ultra-Fine Grain Structure by Combination of Strain Effects

2016 ◽  
Vol 685 ◽  
pp. 487-491 ◽  
Author(s):  
Mikhail Chukin ◽  
Marina Polyakova ◽  
Alexandr Gulin ◽  
Olga Nikitenko
Keyword(s):  
Steel Wire ◽  
Continuous Method ◽  
Grain Structure ◽  
Strain Effect ◽  
Strain Effects ◽  
Fine Grain ◽  
Wide Range ◽  
Processing Modes ◽  
Efficiency Estimation ◽  
Metal Products

It is shown that combination of strain effects leads to possessing the ultra-fine grain structure in carbon wire. The continuous method of wire deformation nanostructuring was developed on the basis of simultaneous applying of tension deformation by drawing, bending deformation when going through the system of rolls and torsional deformation on a continuously moving wire. One of the main advantages of the developed method is that various hardware devices and tools already applied for steel wire production can be used to implement this method thus simplifying its introduction to the current industrial equipment. The efficiency estimation of the developed continuous method of deformation nanostructuring was carried out using carbon wire with different carbon content. It is shown that the mechanical properties of the wire after combination of different kinds of strain can vary over a wide range. This method makes it possible to choose such modes of strain effect, which can provide the necessary combination of strength and ductile properties of carbon wire depending on its further processing modes and application.

Microstructural Changes of Welded Zn-AI Alloy

1994 ◽  
Vol 367 ◽  
Author(s):  
Yao Hua Zhu
Keyword(s):  
Phase Transformation ◽  
Early Stage ◽  
Dendritic Structure ◽  
Metastable Phases ◽  
Grain Structure ◽  
Al Alloy ◽  
Cast State ◽  
Microstructural Changes ◽  
Fine Grain ◽  
Ageing Processes

AbstractExtruded eutectoid Zn-Al alloy was welded by a melt of the same eutectoid alloy. Two different microstructures were observed in the joint part and the bulk of the welded alloy. Typical dendritic structure of as cast Zn-Al alloy was observed in the joint part of the welded alloy. The bulk ofthe welded Zn-Al alloy appeared as fine grain structure. Two different metastable phases η'T decomposed from η's of chilled as cast state and η'E of extruded state were found to be unstable during early stage of ageing. A four phase transformation occurred after the decompositions of these two metastable phases of η'T. Microstructures of both joint part and bulk of the welded alloy were investigated parallely during ageing processes.

Sign in / Sign up

Export Citation Format

Share Document