Ultra-Fine Grained Fe-32%Ni Alloy Processed by Multi-Axial Forging

2010 ◽  
Vol 97-101 ◽  
pp. 187-190 ◽  
Author(s):  
Bao Jun Han
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Microstructure Evolution ◽  
Strain Path ◽  
Internal Stresses ◽  
Deformation Bands ◽  
Fine Grained ◽  
Transmission Electron ◽  
Ni Alloy ◽  
Equiaxed Grains

The Fe-32%Ni alloy was multi-axially forged at the temperature of 873K and strain rate of 10-2s-1, then the microstructure evolution in Fe-32%Ni alloy during deformation was investigated by the transmission electron microscopy (TEM). The results show that the grain size decreases with strain. The severe plastic deformed microstructure is characterized by the ultra-fine equiaxed grains and high internal stresses. The microstructure evolution mechanism is presented as the following: firstly, the dislocations accumulate as deformation bands in some directions with the progress of deformation; then the cellular structured subgrains are formed by continuous intersecting of deformation bands for the changing of strain path; eventually, the ultra-fine structured grains are formed by the subgrains rotation and the dislocations rearrangement.

Grain Refinement of Fe-32%Ni Alloy by Multi-Axial Forging

2011 ◽  
Vol 80-81 ◽  
pp. 18-21
Author(s):  
Xiao Juan Wang ◽  
Bao Jun Han
Keyword(s):  
Electron Microscopy ◽  
Microstructure Evolution ◽  
Large Angle ◽  
Optical Microscope ◽  
Electron Back Scatter Diffraction ◽  
Deformation Bands ◽  
Transmission Electron ◽  
Ni Alloy ◽  
Cumulative Strain ◽  
Austenite Grains

The effect of strain on the microstructure evolution of Fe-32%Ni alloy during multi-axial forging at the temperature of 500°C and a strain rate of 210-2 s-1 was investigated by optical microscope (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron back scatter diffraction (EBSD) observations. The results show that the austenite grains were greatly refined with increasing cumulative strain, and the microstructure evolution during multi-axial forging can be summarized as such a process that deformation bands crossing each other subdivide the original austenite grain into several sub-grains and then these sub-grains are subdivided into more small ones and gradually angled to new independent grains with their boundaries transformed into large angle boundaries in subsequent compression.

Microstructural Characterization, Mechanical Properties and Wear Resistance of TiCP Reinforced Ni-Alloy Coatings by Laser Synthesis

2000 ◽  
Author(s):  
D. L. Tu ◽  
A. Kar ◽  
X. L. Wu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Wear Resistance ◽  
Chemical Reaction ◽  
Phase Interface ◽  
High Fracture Toughness ◽  
Transmission Electron ◽  
Ni Alloy ◽  
The Matrix

Abstract Titanium carbide particle (TiCp)-reinforced Ni alloy composite coatings are synthesized by laser cladding using a cw 3 kW CO2 laser. Two kinds of coatings are possible in terms of the origin of TiCp: undissolved TiCp and in-situ generated TiCp. The former originates from the TiCp pre-coated on the sample whereas the latter from in-situ chemical reaction between titanium and graphite in the molten pool during laser irradiation. For the coating reinforced by TiCp formed in-situ, the sub-micron TiCp particles are formed and uniformly distributed because of the in-situ reaction and trapping effect during rapid solidification. Graded distribution of TiCp is obtained on a macro scale. The volume fraction increases from 1.86% at the coating-substrate interface to 38.4% at the coating surface. For the coating reinforced by undissolved TiCp, analytical transmission electron microscopy (ATEM) and high resolution transmission electron microscopy (HRTEM) observations show the existence of the epitaxial growth of TiC, the precipitation of CrB and M23C6, and the chemical reaction between Ti and B elements around phase interfaces of undissolved TiCp. In the matrix near the phase interface of undissolved TiCp, the loading curve obtained by nanoindenter exhibits pop-in phenomena due to the plastic deformation of cracks or debonding of TiCp from the matrix. For TiCp generated in-situ, no pop-in mark appears, indicating high fracture toughness. Coating with TiCp generated in-situ exhibits higher hardness and modulus than the coating with undissolved TiCp at regions near the phase interface. The coating reinforced by TiCp generated in-situ also displays higher impact wear resistance and abrasive wear resistance compared to the coatings with undissolved TiCp and without TiCp respectively.

Demountable polished extra-thin sections and their use in transmission electron microscopy

1981 ◽  
Vol 44 (335) ◽  
pp. 357-359 ◽  
Author(s):  
D. J. Barber
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Epoxy Resin ◽  
Essential Feature ◽  
Heterogeneous Materials ◽  
Glass Slide ◽  
Thin Sections ◽  
Fine Grained ◽  
Transmission Electron ◽  
Polished Side

The advantages of polished ultra-thin sections (PUTS) in the study of very fine-grained materials, such as occur in some meteorites, have been illustrated by Fredriksson et al. (1978) whose technique is based on the earlier work of Beauchamp and WiUiford (1974). An essential feature of such methods for friable and heterogeneous materials is the use of a medium, usually an epoxy resin, to consolidate and partially impregnate them. Normally one polished side of the specimen is bonded to a glass slide during preparation, and the finished PUTS are integral with the slide on completion. PUTS are typically 2-5 microns in thickness.

Microstructure Evolution of Hydrogenated Ti6Al4V Alloy during Compression

2012 ◽  
Vol 190-191 ◽  
pp. 517-521
Author(s):  
Bao Guo Yuan ◽  
Qiang Chen ◽  
Hai Ping Yu ◽  
Ping Li ◽  
Ke Min Xue ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dislocation Density ◽  
Microstructure Evolution ◽  
Room Temperature ◽  
True Strain ◽  
True Stress ◽  
Compression Tests ◽  
Transmission Electron ◽  
Good Repeatability

Compression tests of the hydrogenated Ti6Al4V0.2H alloy were carried out using an Instron 5569 machine at room temperature. True stress-strain curves of the hydrogenated Ti6Al4V0.2H alloy under different compressive strains were obtained. Microstructure evolution of the hydrogenated Ti6Al4V0.2H alloy during the process of compression was investigated by optical microscopy and transmission electron microscopy. Results show that true stress-true strain curves of Ti6Al4V0.2H alloy have good repeatability. The deformation of grains, the dislocation density and slipping evolution during the process of compression are discussed.

Growth of TiN/AlN Superlattice by Pulsed Laser Deposition

2002 ◽  
Vol 750 ◽  
Author(s):  
H. Wang ◽  
A. Gupta ◽  
Ashutosh Tiwari ◽  
X. Zhang ◽  
J. Narayan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Pulsed Laser Deposition ◽  
High Speed ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Internal Stresses ◽  
Layer By Layer ◽  
Special Configuration ◽  
Transmission Electron

ABSTRACTTiN-AlN binary-components have attracted a lot of interests in coatings of high speed cutting tools, due to their higher oxidation resistance, higher hardness, lower internal stresses and better adhesion. Especially, nanometer-scale multilayer structures of AlN/TiN show superior structural and mechanical properties due to their tremendous interface area and become one of the promising candidates for superhard coatings. Here we present a novel method to grow highly aligned TiN/AlN superlattice by pulsed laser deposition. In this method TiN and AlN targets are arranged in a special configuration that they can be ablated in sequence, giving alternate layer by layer growth of TiN(1nm)/AlN(4nm). X-ray diffraction and transmission electron microscopy (TEM) analysis showed the structure to be cubic for both TiN and AlN in the nanoscale multilayers. Microstructure and uniformity for the superlattice structure were studied by TEM and Scanning transmission electron microscopy with Z-contrast (STEM). Nanoindentation results indicated a higher hardness for this new structure than pure AlN and rule-of-mixtures value. Four point probe electrical resistivity measurements showed overall insulating behavior.

Synthesis and Characterization of Plasma Synthesized Nanostructured Magnesia-Yttria Based Nanocomposites

2007 ◽  
Vol 1056 ◽  
Author(s):  
Jafar F. Al-Sharab ◽  
Rajendra Sadangi ◽  
Vijay Shukla ◽  
Bernard Kear
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Chemical Mapping ◽  
X Ray Diffraction ◽  
Fine Grained ◽  
Transmission Electron ◽  
Spray Method ◽  
Average Grain Size

ABSTRACTPolycrystalline Y2O3 is the material of choice for IR windows since it has excellent optical properties in the visible, and near infra-red band. However, current processing methods yield polycrystalline Y2O3 with large grain size (> 100 μm), which limits the hardness and erosion resistance attainable. One way to improve strength is to develop an ultra-fine grained material with acceptable optical transmission properties. To realize a fine-grained ceramic, one approach is to develop a composite structure, in which one phase inhibits the growth of the other phase during processing. In this study, Y2O3-MgO nanocomposite with various MgO content (20, 50 and 80 mol%) were synthesized using plasma spray method. Extensive characterization techniques including x-ray diffraction, scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Energy Dispersive spectrometry (EDS) were employed to study the synthesized powder as well as the consolidated sample. Transmission Electron Microscopy, as well as EDS chemical mapping, revealed that the consolidated sample have bi-continuous MgO-Y2O3 nanostructure with an average grain size of 200 nm.

Sign in / Sign up

Export Citation Format

Share Document