Advanced Mechanical Properties and Deformation Mechanisms of Bulk Nanostructured Materials
Advances in Nanomaterials and Plastic Deformation
Residual Stresses VIII
Silicon Carbide and Related Materials 2010
Advances in Metal Matrix Composites
Advanced Material Science and Technology
Novel Materials, Coats and Nanoengineering
Explosion, Shock Wave and High-Energy Reaction Phenomena
Researches in Powder Metallurgy
Characterization of Technological Materials
Applied Electromagnetic Engineering
Nanomaterials by Severe Plastic Deformation: NanoSPD5
Progress in Positron Annihilation
Novel Materials, Coats and Nanoengineering
摘要: A unique, original hybrid technological device, developed by the authors of the article, enabling the application of lots of different surface engineering methods in one technological process, including arc evaporation, ion nitriding, ion etching, ion implantation and electron beam evaporation is presented. The hybrid technological device has technical possibilities for the simultaneous realisation of different surface engineering methods in the same vacuum chamber. This results in the realization of advanced technological processes with the use of different surface engineering methods for forming the coating’s properties in one multi-stage technological process. Different surface engineering methods use different plasma sources and different methods of the atmosphere creation and often require different supply and control systems. A possibility of combining a few different surface treatment methods in one technological process is provided by a unique hybrid device. Selected applications of hybrid surface engineering technologies executed with the use of this original hybrid device, i.e. creation of the nano-multilayer and nano-composite Cr/Ni-Cr3C2 coatings increasing the erosion wear resistance and creation of multi-layer coatings with increased thermal resistance – Thermal Barrier Coating (TBC) are presented
摘要: The goal of this paper is to present the structure and properties of the magnesium cast alloys in as-cast state and after heat treatment. Moreover the purpose of this paper is to extend a complex evaluation of magnesium alloys after laser surface treatment and the new methodology to determine thermal characteristics of magnesium alloy using the novel Universal Metallurgical Simulator and Analyzer Platform (UMSA). The presented results concern X-ray qualitative and quantitative microanalysis as well as qualitative X-ray diffraction method, light and scanning microscope.
摘要: Creating a small amount of ultrafine grained metals by severe plastic deformation, for example using equal channel angular pressing, is possible in many research laboratories. However, industrial production of these materials is lagging behind because of the lack of industrially viable severe plastic deformation processes. One attempt to change this situation is based on the concept of incremental equal channel angular pressing developed by the University of Strathclyde and Warsaw University of Technology. The paper describes the path the researchers took to develop the process starting from finite element simulation, through tool design and process implementation, to material characterisation. Examples of various process configurations, which enable obtaining UFG bars, plates and sheets are given and possible future developments discussed.
摘要: Advanced materials manufacturing methods require clean, non-polluting, high speed and precise processes, and should result in highly reliable final products. However, traditionally, many functional materials are synthesized by slow reaction techniques that are both energy and time consuming. In such cases there is strong demand for more appropriate materials processing methods that could offer increased rapid reaction rates and energy efficiencies, and be environmentally safe. Electric discharge assisted mechanical milling (EDAMM) is a new and exciting materials processing technique which combines the attributes of conventional mechanical and mechanochemical milling with the several additional processing effects which can be generated by the simultaneous application of electric discharges. It is shown that EDAMM can be applied to synthesize a range of functional materials in a matter of minutes, rather than the hours or days required using traditional techniques. This presentation provides an overview of recent developments in the EDAMM method and its application to rapid materials processing, and the synthesis of certain functional materials. In this report, we demonstrate the versatility of EDAMM by; (i) synthesis of hard materials, (ii) synthesis of functional oxides used in electronic, magnetic and optical applications, (iii) rapid reduction reactions including extraction of metals from oxides and sulfides and (iv) synthesis of fine metallic and nonmetallic powders and (v) formation of nano- fragments, including carbon nanoribbons and iron oxide nanorods.
摘要: Due to its suitable physical properties and good biocompatibility, the titanium (Ti) can be used for development of porous structures for biomedical applications. The state of art in the field of corrosion resistance showed problems with corrosion analysis of porous metals. Therefore, it is essential to understand the influence of porosity of metals on corrosion parameters. The aim of this study was to investigate the corrosion resistance of highly porous titanium scaffolds for biomedical application. The Ti scaffolds were fabricated by powder metallurgy technique. The total porosity of the scaffolds ranged from 45 to 75%. The cast Ti sample was also tested for comparison. The electrochemical behavior of the Ti samples was monitored by electrochemical impedance spectroscopy (EIS) and potentiodynamic method at the room temperature. All electrochemical experiments were performed by a three-electrode technique in a cell containing a 0.9% NaCl electrolyte solution. With use of AAF, the active area of porous Ti was estimated. The porous Ti with porosity of 75% shows a better resistance to corrosion than the other porous Ti scaffolds. However, the corrosion resistance of Ti scaffolds was lower than cast Ti.
摘要: The aim of this study was to investigate the homogeneity of the bulk nanocrystalline titanium rods obtained by Hydrostatic Extrusion (HE). The investigated material was commercially pure titanium grade 2. The final products of extrusion were nanocrystalline rods with diameters of 7 and 10 mm and lengths of about 250 mm. The size and shape of the grains were examined on transverse sections using transmission electron microscopy (TEM). The grain size was determined by the average grain equivalent diameter d2. The grain size diversity was quantified in terms of the equivalent diameter coefficient of variation CV (d2). The samples for the microscopic analyses were cut from various regions of the rods i.e. top, end, centre, and from surface of the rods. In all the samples, the average grain size determined on transverse sections was about 70 nm and the nano-grains in the various regions of the rods were similar in the shape. The examinations demonstrated that the nanostructure of the extruded rods was homogeneous. This observation was confirmed by the results of microhardness measurements.
摘要: Thermomechanical treatment was applied to a binary NiTi alloy in order to improve its functional properties by forming nanocrystalline structure of the alloy. The alloy deformation was obtained by cold rolling combined with transverse movement of the rolls. This technique allowed us to obtain high strain (c ≈ 6) for the relatively large specimens. Subsequently, the samples were annealed in the temperature range 300 -500oC in order to form a nano-, submicro –and/or microcrystalline structure. The evolution of the structure and associated changes of the transformation sequences and functional properties were studied with the use of TEM, X-ray phase analysis, DSC and bend and free recovery ASTM tests. A mixed amorphous/crystalline structure was obtained after severe deformation, the martensitic transformation was completely suppressed in the sample. Annealing at lower temperatures caused formation of nanocrystalline structure that grew to the microcrystalline and finally well-defined polygonized structure in annealed at 500oC specimens.
摘要: In the paper the concept of structure refinement due to mechanical twinning is discussed. It is postulated that the process of structure refinement may occur when dominant crystal shear proceeds across twin-matrix interface (Mode 2). Contrary, if the crystal shear proceeds parallel to the interface (Mode 1) no condition for structure refinement is satisfied. The conditions of the structure refinement and no structure refinement are shown taking example of tensile Cu-8%at. Al single crystals of two orientations [1 4 5] and [1 1 2] tested in liquid nitrogen. The tensile characteristics are therefore divided into stages associated with the Mode 1 and Mode 2, which correspond to the fact whether refinement of single crystal structure is present or not, as it is proved by the EBSD analysis. The performed analysis showed that structure refinement consists of formation of regions of new orientations, where the most common feature is the II order twinning (the case [1 4 5]) supported by other regions of specific orientations necessary to accommodate mainly the transfer of crystal twin shear across the twin-matrix interface. Moreover, if the II order twinning plays the dominating function (the case [1 1 2]) higher order twins are to bring into operation to assure further ductility of a deformed sample.
摘要: The new hybrid technology is a combination of electron beam evaporation and arcevaporation processes, enabling the creation of the anti-erosion multilayer composite coating Ni/Cr- Cr3C2 with different volume of Cr3C2 filling in soft Ni/Cr matrix. The soft matrix made of Ni/Cr alloy and hard filling of Cr3C2 are created at the same time and directly during the electron beam and arc-evaporation process. Changes of the parameters of the hybrid process, i.e. pressure, current of arc discharge and substrate bias voltage Ubias, make it possible to control the volume of Cr3C2 and are a factor in filling the soft Cr/Ni matrix with carbides Cr3C2. With the use of the developed surface treatment hybrid technology, the multilayer composite coating Ni/Cr-Cr3C2 were obtained. For all composite layers created, the material properties, such as morphology, phase and chemical compositions, hardness, and Young modulus were investigated. The paper presents the original technological equipment, methodology, and technological parameters for the creation of the composite coating Ni/Cr-Cr3C2.