Xenia Molodova

Laser powered heating stage in a scanning electron microscope for microstructural investigations at elevated temperatures

A laser powered heating stage designed for application in high vacuum environment of a scanning electron microscope (SEM) is presented. It was developed to observe and characterize microstructural changes in crystalline materials at elevated temperatures up to 1000 degrees C. The approach utilizes the power output of a commercial infrared diode laser in order to heat up specimens without interference with the electronic system of the SEM. The heating stage can be used in combination with any standard characterization technique applicable for SEMs--electron backscatter diffraction, orientation contrast imaging, x-ray energy dispersive spectrometry, etc. The results of test measurements are presented.

On the Thermal Stability of ECAP Deformed FCC Metals

Pure Cu, CuZr and an Al-alloy were processed by Equal Channel Angular Pressing (ECAP) at room temperature applying route Bc. Microstructure evolution during ECAP and subsequent annealing was investigated. The deformed and annealed states were characterized by EBSD, TEM and microhardness tests. The microstructure variation was recorded and compared to the behavior of conventional cold rolled material. The study revealed a very low thermal stability of ECAP deformed pure Cu samples compared to cold rolled material with same total strain. However, the thermal stability was significantly improved by alloying with Zr. In contrast, ECAP deformed Al-alloy showed higher thermal stability than cold rolled material.

ECAP Processed Copper during Deformation and Subsequent Annealing

Microstructure and texture evolution of pure copper (99.95%) after Equal-Channel Angular Pressing (ECAP) and subsequent heat treatment were investigated. Initially the material was subjected up to twelve passes with a 90° die angle using route Bc. This resulted in an equivalent strain of 13.8. After deformation the samples were annealed at different temperatures. The deformed and annealed states were characterized by using the crystallographic texture analysis, EBSD measurements and microhardness tests.

Recrystallization Behaviour of Cold Rolled Aluminum Alloy AA 3103 in a Magnetic Field

The recrystallization behavior of 71% cold rolled aluminum alloy 3103 was investigated by measuring the crystallographic texture and the grain microstructure during heat treatment at 288°C, 310°C and 330°C in a magnetic field of 17 T. The results revealed that the application of a magnetic field substantially enhances recrystallization kinetics.

Texture Evolution during ECAP and Subsequent Annealing of an AlMg1Mn0.14 Alloy

The texture evolution during Equal-Channel Angular Pressing (ECAP) of an AlMg1Mn0.14 alloy was investigated. The material was subjected up to eight passes with a 90° die angle using route A. This resulted in an equivalent strain of 9.2. The obtained ECAP textures were compared to conventional simple shear textures. In order to investigate the thermal stability of severely deformed material the samples were annealed at several temperatures. The texture evolution during heat treatments was analysed.

Annealing Behavior of ECAP Deformed Aluminum Alloy 3103

In the present study the microstructure evolution of the aluminum alloy 3103 subjected to ECAP up to eight passes applying route Bc was investigated after deformation and subsequent isothermal annealing. The deformed and annealed states were analyzed by SEM, EBSD, optical microscopy and microhardness tests. It will be demonstrated that this ECAP deformed material shows an increased stability against discontinuous recrystallization with growing number of passes.