EFFECT OF SEVERE PLASTIC DEFORMATION ON STRUCTURE AND PROPERTIES OF AUSTENITIC AISI 316 GRADE STEEL
The article presents results of investigation of structure and properties of austenitic steel grade AISI 316 after application of Equal Channel Angular Pressing (ECAP) at the temperature of approx. 290C. The ECAP method leads to significant improvement of strength of investigated material. Investigation of structure was made by combination of TEM and FEG SEM together with EBSD. Statistic evaluation of angular disorientation and of size of grains/sub-grains was also made with use of electron diffraction (EBSD) in combination with scanning electron microscope FEG SEM Philips. It was proven that the ECAP method enables obtaining of ultra fine-grained austenitic structure. It was established with use of the EBSD technique that after 8 passes through the ECAP die the sub-grains with misorientation angles smaller than 10 formed less than 20% of the final structure. Average size of austenitic grains with high-angle boundaries after 8 passes was approx. 0.1m.
Microstructure of ultrafine-grained Al produced by severe plastic deformation
Purpose: The structure of Al subjected to severe plastic deformation by means of compression with oscillatory torsion and by combined method (compression followed by compression with oscillatory torsion) were investigated. Design/methodology/approach: Al samples were deformed at torsion frequency (f) changed from 0 Hz (compression) to 1.6 Hz under a constant torsion angle (α) ≈6° and compression speed (v)=0.1mm/s. For combined methods the samples were compressed for strain e= 0.7 and next deformed at mentioned parameters of compression with oscillatory torsion. Structural investigations were conducted by using light microscopy (LM) and transmission electron microscopy (TEM). Findings: The structural analysis made by TEM shows that the processing by compression with oscillatory torsion ensures obtaining a structure (at selected parameters) with a mean grain size ≈ 1.6μm. Combined methods of deformation lead to grain refinement to about ≈ 0.9μm moreover material with uniform ultra-fine grained (UFG) microstructure was obtained. Research limitations/implications: The understanding in refinement of Al structure could help to modify the process and design deformation parameters. Practical implications: The knowledge of the characteristic features of unconventionally deformed materials will provide the usefulness of the employed method to produce materials having the desirable functional properties. Originality/value: Oscillatory compression is a deformation procedure applied to achieve large strains. However there is no studies on evolution of the microstructures during deformation by using mentioned mode. This paper provides these information’s.
Electrochemical detection of copper(II) at a gold electrode modified with a self-assembled monolayer of penicillamine
A penicillamine (PCA) self-assembled monolayer (SAM) was prepared on a gold electrode. It has been found that the modified electrode exhibited a selective response to copper ions. As demonstrated by cyclic voltammetric experiments, the SAM-based electrode showed an attractive ability to preconcentrate efficiently traces of copper(II) from solutions. Under optimum conditions, the anodic peak current was proportional to the concentration of Cu(II) in the range from 8.0 × 10−7 to 1.0 × 10−4 M with a detection limit of 4.0 × 10−7 M. Moreover, this modified gold electrode is also characterized by excellent repeatability, showing a relative standard deviation of 3.2% for nine successive measurements of 1.0 × 10−5 M Cu(II). The PCA/Au SAM gold electrode was used for the determination of Cu(II) in a tap water sample and the results showed a good agreement with the data obtained by atomic emission spectrometry.