Subgrain rotation during in-situ annealing of Al-6 wt% Ni in the HVEM

1984 ◽  
Vol 42 ◽  
pp. 476-477
Author(s):  
H. M. Chan ◽  
F. J. Humphreys
Keyword(s):  
Volume Fraction ◽  
Thin Foil ◽  
High Volume ◽  
Second Phase ◽  
Dispersion Parameters ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
Subgrain Rotation ◽  
Alloy Heat

Recently a series of commercial aluminum alloys has been developed (based on eutectic compositions), which contain a high volume fraction (∼10%) of second phase [1,2]. This paper describes the behavior of one such alloy, when thinfoil specimens (75% defd.) were annealed in-situ in the HVEM.The eutectic alloy studied was Al-6 wt% Ni. The alloy heat treatment and particle (Al3Ni) dispersion parameters are given in Table 1. Three-mm discs were punched from as-deformed material. Thin foil specimens were prepared by standard jet polishing techniques. In-situ annealing was carried out in the AEI EM7 high voltage electron microscope at 500 kV, using a platinum ribbon heating stage [3].

In-situ electrical-resistivity measurements in the high-voltage electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 68-69
Author(s):  
W. E. King
Keyword(s):  
Electrical Resistivity ◽  
Electron Microscope ◽  
High Voltage ◽  
Resistivity Measurements ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Wide Range ◽  
Helium Gas

A side-entry type, helium-temperature specimen stage that has the capability of in-situ electrical-resistivity measurements has been designed and developed for use in the AEI-EM7 1200-kV electron microscope at Argonne National Laboratory. The electrical-resistivity measurements complement the high-voltage electron microscope (HVEM) to yield a unique opportunity to investigate defect production in metals by electron irradiation over a wide range of defect concentrations.A flow cryostat that uses helium gas as a coolant is employed to attain and maintain any specified temperature between 10 and 300 K. The helium gas coolant eliminates the vibrations that arise from boiling liquid helium and the temperature instabilities due to alternating heat-transfer mechanisms in the two-phase temperature regime (4.215 K). Figure 1 shows a schematic view of the liquid/gaseous helium transfer system. A liquid-gas mixture can be used for fast cooldown. The cold tip of the transfer tube is inserted coincident with the tilt axis of the specimen stage, and the end of the coolant flow tube is positioned without contact within the heat exchanger of the copper specimen block (Fig. 2).

Dislocation Dynamics in Icosahedral Al-Pd-Mn Single Quasicrystals

2000 ◽  
Vol 643 ◽  
Author(s):  
Ulrich Messerschmidt ◽  
Martin Bartsch ◽  
Bert Geyer ◽  
Lars Ledig ◽  
Michael Feuerbacher ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Stress Exponent ◽  
High Voltage ◽  
Dislocation Dynamics ◽  
Slip Mechanism ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
Slip Planes ◽  
Slip Traces

AbstractThe paper reviews results from in situ straining experiments on Al-Pd-Mn single quasicrystals in a high-voltage electron microscope. Slip planes were determined from the orientation and width of slip traces. Dislocations are generated by a specific cross slip mechanism. On some slip traces, dislocations move at two distinctly different velocities. A stress exponent was determined on a single dislocation by observing its displacement under decreasing load. The in situexperiments reveal the behaviour of individual dislocations in a temperature range where the deformation of bulk specimens is strongly affected by recovery.

Mechanical Properties of Hot-Pressed B4C-TiB2 Composites Synthesized from B4C-TiO2 and B4C-TiC

2021 ◽  
Vol 902 ◽  
pp. 81-86
Author(s):  
Shu Mao Zhao ◽  
Ling Ran Zhao
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Volume Fraction ◽  
Raw Materials ◽  
Ceramic Composites ◽  
In Situ Synthesis ◽  
Second Phase ◽  
Pressing Method ◽  
The One

In this study, B4C-TiB2 ceramic composites were manufactured by hot pressing method. The raw materials for the in-situ synthesis of TiB2 were TiO2 and TiC. After being sintered at 1900°C for 60min under a pressure of 30MPa, compact composites samples with a TiB2 volume fraction range from 0 to 11.05% were prepared. The relative density, fracture toughness and flexural strength of different sample were tested. Microstructures on the fracture surface were studied by SEM. The result shows that B4C-TiB2 ceramic composites sintered from B4C-TiC had a better mechanical property than the one sintered from B4C-TiO2. When the content of TiB2 (reacted from TiC) was 11.05vol.%, the strength and toughness of B4C-TiB2 ceramics can reach 598MPa and 6.45MPa·m1/2. The toughening mechanisms of B4C-TiB2 composites include micro-crack toughening and energy consumption by the pulling out process of second phase.

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