O. Man

Strain Mapping by Scanning Low Energy Electron Microscopy

The use of the scanning low energy electron microscopy (SLEEM) has been slowly making its way into the field of materials science, hampered not by limitations in the technique but rather by relative scarcity of these instruments in research institutes and laboratories. This paper reports the results obtained from an investigation of the microstructure of ultra fine-grained (UFG) copper fabricated using equal channel angular pressing (ECAP) method, namely in the as-pressed state and after annealing. SLEEM is very sensitive to the perfection of crystal lattice and using SLEEM, local strain can be effectively imaged.

Use of the Powder Liquid Method for Aluminide Diffusion Coatings Formation on Inconel 713LC Nickel-Based Superalloy

Powder liquid method was used for aluminides diffusion coatings formation on the Inconel 713LC nickel-based superalloy. Two different powder mixtures (Al and Al + Si) in organic binder solution were prepared. Coatings deposition onto the substrate surface was realized by spraying. Two-stage heat treatment under the argon-flow atmosphere was designed. First stage at 200°C was used to decompose organic binder. In the second stage at 1000°C the elements from the coating interact with the substrate. Protective intermetallic layer and an interaction zone between the layer and substrate start to form. Elements interaction and phase transformations during annealing at 1000°C up to 600 min were studied. For this study the light microscopy, scanning electron microscopy, energy dispersive microanalysis, x-ray diffraction phase analysis, microhardness measurement, and image analysis methods were used.

Microstructural changes of ECAP-processed magnesium alloy AZ91 during cyclic loading at different stress-amplitude levels

Microstructural changes of magnesium alloy AZ91 after fatigue loading in the EX-ECAP state were evaluated using EBSD. It was found that both the number fraction of low-angle boundaries and parameter KAM decreased after the testing at a stress amplitude of 160 MPa but started to increase with the increasing stress amplitude. This behaviour can be explained with a mutual influence of dislocation accumulation (which is stronger with a higher stress amplitude) and dynamic softening (which is weaker with a decreasing number of cycles/cycles to failure). The average grain size remained almost unchanged except at a stress amplitude of 180 MPa, which could have been caused by certain conditions allowing an ideal development of both mentioned phenomena.

Analysis of Cracked Spring Washer for Sleeper-Rail Joints

The paper deals with the qualitative, quantitative, and phase analyses of particles that were found during the metallographic analysis of a cracked spring washer made of silicon spring steel 38Si7, with the aim of ruling out the client’s suspicion of possible initiation of graphitization in the course of the heat treatment. The problem is solved via metallographic analysis using light microscopy, scanning electron microscopy including EDS microanalysis of the chemical composition and EDS line analysis.