scholarly journals Evolution of the Microstructure of a CuCr1Zr Alloy during Direct Heating by Electric Current

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1074
Author(s):  
Miroslav Karlík ◽  
Petr Haušild ◽  
Philippe Pilvin ◽  
Denis Carron
Keyword(s):  
Hardness Test ◽  
Electrical Current ◽  
Grain Structure ◽  
Strain Fields ◽  
Direct Electrical Current ◽  
Transmission Electron ◽  
The Matrix ◽  
Coarsening Kinetics ◽  
Wagner’S Theory ◽  
Vickers Hardness Test

Round tensile test specimens of an age-hardened CuCr1Zr alloy were subjected to direct electrical current heating in a Gleeble thermal–mechanical simulator at 800 °C. The mechanical properties were monitored by the Vickers hardness test, and the changes in the grain structure were examined by light metallography. A quantitative analysis of the size and distribution of fine precipitates during annealing was carried out using transmission electron microscopy (TEM). The grain structure showed a gradient corresponding to the gradient of the temperature on the test piece. Annealing for 60 s at 800 °C resulted in a partially (~50%) recrystallized structure with new grains about 45 μm in diameter. In the as-delivered condition, TEM documented tiny (1 to 4 nm) coherent chromium precipitates inducing strain fields in the matrix. During overaging, the particles lost their coherence and gradually coarsened up to a mean diameter of 40 nm after 300 s at 800 °C. The coarsening kinetics obeys Lifshitz, Sloyzov, and Wagner’s theory.

scholarly journals Effect of Two-Stage Homogenization Heat Treatment on Microstructure and Mechanical Properties of AA2060 Alloy

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 40
Author(s):  
Chaoyang Chaoyang ◽  
Guangjie Guangjie ◽  
Lingfei Lingfei ◽  
Fei Fei ◽  
Lin Lin
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Cast Alloy ◽  
Hardness Test ◽  
Test Methods ◽  
Al Alloy ◽  
Two Stage ◽  
Homogenization Treatment ◽  
Transmission Electron ◽  
The Matrix

The microstructure evolution of AA2060 Al alloy containing Li during two-stage homogenization treatment was investigated by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), differential scanning calorimeter (DSC), transmission electron microscopy (TEM), mechanical properties and Vickers micro-hardness test methods. The results demonstrate that severe precipitation of θ(Al2Cu) and S(Al2CuMg) phase existed in the as-cast alloy, especially in the center position. Cu elements were concentrated at grain boundary and gradually decreased from the boundary to the interior. Numerous eutectic phases of θ(Al2Cu) and S (Al2CuMg) containing Zn and Ag elements were segregated at grain boundaries. The overheating temperature of the as-cast alloy is 497 °C. After two-stage homogenization treatment, the θ(Al2Cu) and S (Al2CuMg) in the surface, middle and center positions were completely dissolved into the matrix, thus achieved uniform homogenization effect. Moreover, water cooling could prevent the precipitation after homogenization, which provided good performance of the studied alloy. The optimum two-stage homogenization treatment of AA2060 alloy was 460 °C/4 h + 490 °C/2 4 h. The homogenization kinetic analysis was discussed as well.

scholarly journals Annealing effect of micro-alloying on the microstructure and properties of Cu-10Zn alloy

2019 ◽  
Vol 136 ◽  
pp. 01015
Author(s):  
Wei Chen ◽  
Jiarui Hu ◽  
Yi Xie ◽  
Hengyi Zhou ◽  
Chao Feng ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Aging Process ◽  
Conductivity Measurement ◽  
Hardness Test ◽  
Precipitation Strengthening ◽  
Strengthening Effect ◽  
Electrical Conductivity Measurement ◽  
Microstructure And Properties ◽  
Transmission Electron ◽  
The Matrix

The effect of Fe and P (Ni and Si) on the microstructure and properties of Cu-10Zn alloys has been investigated using hardness test, electrical conductivity measurement, optical microscopy and transmission electron microscopy. γ-Fe precipitates formed during the aging process, but there is almost no effect of precipitation strengthening on the Cu-Zn-Fe-P alloy and sparsely Fe3P precipitates existed in the matrix. After homogenization treatment at 900°C for 2h, hot rolling by 80%, cold rolling by 80%, and ageing treatment at 400°C for 30min, Cu-Zn-Ni-Si alloy obtained good combinations of hardness (219.8HV) and electrical conductivity(28.2%IACS). Ni2Si precipitates formed during aging process and the crystal orientation relationship between matrix and precipitates is:(200)α || (100)δ, [100]α || [010]δ,. Compared with Cu-Zn-Fe-P, Cu-Zn-Ni-Si has finer grains, and the precipitation strengthening effect is more obvious.

Interfacial Particle Bonding Via an Ultrathin Polymer Film on Al2O3 Nanoparticles by Plasma Polymerization

2002 ◽  
Vol 17 (5) ◽  
pp. 981-990 ◽  
Author(s):  
Donglu Shi ◽  
Peng He ◽  
S. X. Wang ◽  
Wim J. van Ooij ◽  
L. M. Wang ◽  
...  
Keyword(s):  
Plasma Polymerization ◽  
Treatment Time ◽  
Hardness Test ◽  
Alumina Nanoparticles ◽  
Al2o3 Nanoparticles ◽  
Particle Bonding ◽  
Transmission Electron ◽  
The Matrix ◽  
Conventional Sintering ◽  
Plasma Treatment Time

To study interfacial particle-to-particle bonding mechanisms, an ultrathin film of pyrrole was deposited on alumina nanoparticles using a plasma polymerization treatment. High resolution transmission electron microscopy experiments showed that an extremely thin film of the pyrrole layer (2 nm) was uniformly deposited on the surfaces of the nanoparticles. In particular, the particles of all sizes (10–150 nm) exhibited equally uniform ultrathin films indicating well-dispersed nanoparticles in the fluidized bed during the plasma treatment. Time-of-flight secondary ion mass spectroscopy experiments confirmed the nano-surface deposition of the pyrrole films on the nanoparticles. The pyrrole-coated nanoparticles were consolidated at a temperature range (approximately 250 °C) much lower than the conventional sintering temperature. The density of consolidated bulk alumina has reached about 95% of the theoretical density of alumina with only a few percent of polymer in the matrix. After low-temperature consolidation, the micro-hardness test was performed on the bulk samples to study the strength that was related to particle-particle adhesion. The underlying adhesion mechanism for bonding of the nanoparticles is discussed.

Analysis of Fine Stress Fields in Metal Matrix Composites Using HOLZ Patterns

2007 ◽  
Vol 539-543 ◽  
pp. 848-853
Author(s):  
M. Shibata ◽  
Yoshito Takemoto ◽  
Ichiro Shimizu
Keyword(s):  
Metal Matrix ◽  
Small Area ◽  
Squeeze Casting ◽  
Stress Fields ◽  
Stress And Strain ◽  
Matrix Composites ◽  
Strain Fields ◽  
Transmission Electron ◽  
Reinforcement Material ◽  
The Matrix

Aluminium alloy composites reinforced with aluminium borate whiskers (ABw), developed recently by SHIKOKU KASEI KOUGYOU Co. Ltd., Japan, were fabricated using squeeze casting. The large mismatch in the coefficients of thermal expansion (CTE) between the reinforcement material and the matrix can generate significant stress and strain in composites during thermal cycling or during fabrication of the composites when using squeeze casting. When a transmission electron microscope is used to irradiate a very small area of a thin film of the material with a convergent electron beam of several nm in diameter, High Order Laue Zone patterns (HOLZ patterns) are obtained. These HOLZ patterns can reveal fine strain fields in the reinforcement materials that are used in composites fabricated using squeeze casting. Each (001) plane in the ABw was rotated towards the [020] direction by up to 0.5 ﾟ. With a unit of nearly 400 nm × 400 nm, each (100) plane was rotated towards the [020] direction in a corkscrew pattern. In addition the strain and the stress generated during the fabrication of the composites were estimated by using the finite element methods taking into account the anisotropies in both the CTE and the elastic modulus of the reinforcement material.

The role of microscopy in the development of metal matrix composites

1992 ◽  
Vol 50 (1) ◽  
pp. 162-163
Author(s):  
Gilles L'Espérance ◽  
David J. Lloyd
Keyword(s):  
Electron Microscopy ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Grain Structure ◽  
Analytical Transmission Electron Microscopy ◽  
Matrix Composites ◽  
Matrix Microstructure ◽  
Transmission Electron ◽  
The Matrix

From the very beginning of the development of metal matrix composites, (MMC's), electron microscopy has played a major role in their development. Thus, analytical transmission electron microscopy, (ATEM), has been used to characterize and study: the reinforcements in MMC's, interfacial reactions and products that can occur at the interface between the matrix and the reinforcement and the detailed matrix microstructure, particularly the dislocation and grain structure and the precipitation/constituent phases. In this presentation, we will review and discuss the contribution of ATEM to each of these points and describe how it provided necessary information in the design and use of these materials. The presentation will mainly discuss Al-based composites although work from Ti and Mg-based composites will also be presented.

Influence of Heat Treatments on Microstructures in an Fe-Co-V Alloy

1974 ◽  
Vol 32 ◽  
pp. 512-513
Author(s):  
S. Mahajan ◽  
M. R. Pinnel ◽  
J. E. Bennett
Keyword(s):  
Single Phase ◽  
Alloy Composition ◽  
Supersaturated Solid Solution ◽  
Cell Formation ◽  
Heat Treatments ◽  
Air Cooling ◽  
Iced Brine ◽  
Transmission Electron ◽  
The Matrix ◽  
Bcc Structure

The microstructural changes in an Fe-Co-V alloy (composition by wt.%: 2.97 V, 48.70 Co, 47.34 Fe and balance impurities, such as C, P and Ni) resulting from different heat treatments have been evaluated by optical metallography and transmission electron microscopy. Results indicate that, on air cooling or quenching into iced-brine from the high temperature single phase ϒ (fcc) field, vanadium can be retained in a supersaturated solid solution (α2) which has bcc structure. For the range of cooling rates employed, a portion of the material appears to undergo the γ-α2 transformation massively and the remainder martensitically. Figure 1 shows dislocation topology in a region that may have transformed martensitically. Dislocations are homogeneously distributed throughout the matrix, and there is no evidence for cell formation. The majority of the dislocations project along the projections of <111> vectors onto the (111) plane, implying that they are predominantly of screw character.

Determination of the phase structure of polymerblends by electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 492-493
Author(s):  
Dr. G. Kaemof
Keyword(s):  
Screw Extruder ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Single Screw Extruder ◽  
Transmission Electron ◽  
The Matrix ◽  
Twin Screw ◽  
Special Case ◽  
Microscopic Investigations

A mixture of polycarbonate (PC) and styrene-acrylonitrile-copolymer (SAN) represents a very good example for the efficiency of electron microscopic investigations concerning the determination of optimum production procedures for high grade product properties.The following parameters have been varied:components of charge (PC : SAN 50 : 50, 60 : 40, 70 : 30), kind of compounding machine (single screw extruder, twin screw extruder, discontinuous kneader), mass-temperature (lowest and highest possible temperature).The transmission electron microscopic investigations (TEM) were carried out on ultra thin sections, the PC-phase of which was selectively etched by triethylamine.The phase transition (matrix to disperse phase) does not occur - as might be expected - at a PC to SAN ratio of 50 : 50, but at a ratio of 65 : 35. Our results show that the matrix is preferably formed by the components with the lower melting viscosity (in this special case SAN), even at concentrations of less than 50 %.

The microstructure of a TiB2/Ti-47 Al composite material

1989 ◽  
Vol 47 ◽  
pp. 674-675
Author(s):  
O. Popoola ◽  
A.H. Heuer ◽  
P. Pirouz
Keyword(s):  
Composite Material ◽  
Ion Beam ◽  
Chemical Properties ◽  
Intermetallic Alloys ◽  
Transmission Electron ◽  
Diamond Polishing ◽  
Al Composite ◽  
The Matrix ◽  
Argon Ion ◽  
And Chemical Properties

The addition of fibres or particles (TiB2, SiC etc.) into TiAl intermetallic alloys could increase their toughness without compromising their good high temperature mechanical and chemical properties. This paper briefly discribes the microstructure developed by a TiAl/TiB2 composite material fabricated with the XD™ process and forged at 960°C.The specimens for transmission electron microscopy (TEM) were prepared in the usual way (i.e. diamond polishing and argon ion beam thinning) and examined on a JEOL 4000EX for microstucture and on a Philips 400T equipped with a SiLi detector for microanalyses.The matrix was predominantly γ (TiAl with L10 structure) and α2(TisAl with DO 19 structure) phases with various morphologies shown in figure 1.

Sign in / Sign up

Export Citation Format

Share Document