Materials Science Forum Vol. 729

Abstract: Al/SiC composites are used especially in automotive and aerospace industry due to the numerous advantageous mechanical properties. These end-products can be produced by casting or powder metallurgical techniques. High strength with high toughness can be reached only by perfect interfacial bonds between the matrix and reinforcing phase. To improve the interfacial bond, one of the methods is the surface coating of the SiC particles. But the metal layer of the reinforcing phase reacts with the matrix due to the high sintering temperature and long sintering time. In our research work the formation of Al-Ni intermetallic phase was investigated by Scanning electron microscopy (SEM) and X-ray diffraction measurements (XRD).

Abstract: The guidewire is a small diameter, steerable wire which facilitates the navigation of the interventional devices such as stent, balloon, or coil in endovascular intervention. The guidewire has an elongated flexible body and a relatively more flexible ribbon tip. The elongated body (shaft) is tapered to the ribbon tip. The composition of the helical coil formed ribbon tip is different than the elongated body. In this article we demonstrate the correlation between the material composition and the kinking resistance of guidewire. The identified metal composition of the core wire was 18-8 stainless steel and the helical coil composed of platinum-nickel alloy and the material of tip bond was tin. The kink angle which caused permanent deformation were significantly higher on the helical coil (=68,3^o) due to the higher flexibility of the helical coil than that was found on the shaft portion (=55^o) (p=0,00032). The remnant angel induced by 90^o kinking on the helical coil was significantly lower (=15^o) than that was observed on the shaft portion (=23,9^o) (p=0,00046). The deformation of the helical coil was smaller due to the higher flexible properties of the platinum-nickel alloy material against the stainless steel.

Abstract: In this study the aluminium sheet bonding properties is investigated. The bonding was performed between 1050 and 3003 Al alloys using mechanical press (eccentric press) or hot rolling (VON ROLL experimental duo mill). The experimental temperatures were 400, 450, 500°C. The goodness of bonding was tested by tensile test and T-peel test. The optimal parameters were developed for the T-peel test. The results obtained from these tests give a good description about the quality of bonding. Structure analysis was also performed by LM and SEM to detect the typical bonding faults.

Abstract: Determining the effect of irradiation on the mechanical properties of reactor pressure vessel during the operational lifetime of a nuclear power plant is crucial from the safe operation point of view. That information is derived from the investigations of specimens made of the same material as the pressure vessel. One of the most commonly used methods is the Charpy test. In order to better use the limited volume of the available space for specimens in the reactor, and further investigate the radiation ageing of used samples, the probe reconstitution by welding is applied. The reconstituted specimen can be investigated three times thus improving the amount of data gained and reducing the radioactive waste. In the presented paper the stud welding technology was investigated, the effect of different stud geometries and weld protection on the quality of the final product will be discussed.

Abstract: Li₆Y(BO₃)₃ and Li₆Gd (BO₃)₃ powders were synthesized using wet chemical method. Lithium-nitrate, yttrium-/gadolinium-nitrate and boric acid solutions were mixed in stoichiometric composition, and a colloidal precipitate was obtained by adjusting the pH of the mixture. Li₆Y(BO₃)₃/Li₆Gd (BO₃)₃ phase formation was achieved by annealing the precursors in the 650700 °C temperature range. The reaction steps were monitored by FTIR and Raman-spectroscopy, and the final products were characterized by X-ray powder diffraction and scanning electron microscope. XRD assessment shows that we obtained LYBO/LGBO as dominant phases after a 24 h treatment at 650 °C.

Abstract: The paper deals with the towers of electric high voltage overhead lines. The target is a relatively simple suspension tower (tension support) made of hot rolled angles. The main aspects of structural design and the structural details are given due to the newly introduced design codes and the former Hungarian ones. The fundamental aim of the paper is to point out the changes according to the new developments. As an important design aid, a set of interactive programs developed by the authors is also shortly introduced.

Abstract: Commercial Cu-ETP drawn copper bar was both mechanically and thermally treated. Repeated cycles of cold rolling and heat treatment with altered parameters were applied on the specimens. Grain boundary character distribution (GBCD) was calculated from the orientation microscopy data. As regards the processing of the orientation data the coincidence site lattice theory was applied. The evolution of the GBCD is discussed in terms of the parameters of cold rolling and heat treatment processes.

Abstract: Microstructural changes and relaxation processes were examined in Fe-Zr based rapidly solidified samples. These phenomena occur far below crystallization temperature in the course of heat treatment, or even at room temperature, induced by absorbed hydrogen.

Abstract: Our company started an alloy development project with the aim of developing an alloy to miniature casting, which meets customer requirements the most. Besides solders and alloys for nuclear usage, the manufacturing of alloys to miniature casting is also a significant business. The development was started based on the requirements of the customers. Model metals are mainly alloys of lead-tin-bismuth and antimony. Adequately, the research concentrated on this alloy system. In the first step, besides the thermal characteristics, the crystallization of dissimilar alloys in the system and crystallized microstrtucture was examined. The thermal features of the crystallization of alloys were examined by calorimetry, while microstructural constituents were examined by metallographic and SEM-EDX examinations.

Abstract: During this study the distortion phenomenon was investigated on selected UHMWPE cups removed from patients, using 3dimensional measurement method. The cups investigated were machined by Metrimed Ltd. from ram extruded Chirulen 1020 type UHMWPE rods. The samples were measured with a 3D touch coordinate measurement device with an accuracy of 3 microns.