Wyniki 1-3 spośród 3 dla zapytania: authorDesc:"Paweł Hyjek"


  Mechanical properties of Ni-Al-Ti-B alloys are discussed in the paper. The samples were tested by compression in a wide range of temperatures and strain rates. The Ni-Al-Ti-B alloy is characterized by high hardness and addition of Ti does not show any significantly negative effect on brittleness. The conducted compression tests demonstrated decrease of yield point and increase of ductility with increase of temperature. The evolution of structure at various strain levels is also reported, especially in the aspect of application of the alloy for working at higher temperatures. Additionally, observations of samples’ surface from the onset of cracking until failure of the sample were performed. Keywords: NiAl-based alloys, mechanical properties, microstructure MIKROSTRUKTURA I WŁAŚCIWOŚCI MECHANICZNE STOPU Ni-Al-Ti-B W artykule przedstawiono wyniki badań dotyczące właściwości mechanicznych stopu Ni-Al-Ti-B. Otrzymano je z testów ściskania prowadzonych w szerokim zakresie temperatur i prędkości odkształcenia. Stop Ni-Al-Ti-B charakteryzuje wysoka twardość, a dodatek tytanu nie wpływa w sposób istotny na wzrost kruchości. Wykonane próby ściskania wykazały obniżenie granicy plastyczności i podwyższenie ciągliwości ze wzrostem temperatury. Przedstawiono także obserwacje zmian strukturalnych przy różnych poziomach odkształcenia, szczególnie w aspekcie przydatności tego stopu do pracy w podwyższonych temperaturach. Dokonano także obserwacji powierzchni próbek od stadium inicjacji pękania aż do zniszczenia. Słowa kluczowe: stopy na osnowie NiAl, właściwości mechaniczne, mikrostruktura.Introduction Studies in the field of new materials for high temperature applications have stimulated interest in alloys based on intermetallic phases, mainly from equilibrium systems of NiAl, FeAl and TiAl. These alloys are characterised by unusual mechanical and physicochemical properties as well as corrosion resistance, making them eligible for operation at [...]

The properties of AISI 316L stainless steel reinforced with TiB2 ceramics sintered by the HT-HP process

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Austenitic steel is a material characterized by high and stable mechanical properties at high temperature as well as high resistance to the aggressive environments. However, TiB2 ceramics is characterized by a unique combination of the properties (high melting point 3127°C, high hardness 33 GPa, high modulus 570 GPa and low density 4.451 g/cm3), which provide opportunities to apply it in a high temperature and corrosive environment. The TiB2 ceramics has a very good resistance to the oxidation, chemical and structural stability at high temperatures, resistance to the thermal shocks and abrasion resistance [1÷5]. Therefore, titanium diboride is the good reinforcing material for composites than for example carbides, which are less stable at high temperature. For several years research on a group of iron-base oxide dispersion strengthened (ODS) alloys were conducted. ODS alloys have been considered as the material of choice for many high temperature applications for a long time, because of their attractive mechanical properties such as outstanding creep and fatigue strengths at temperatures exciding 1000°C. The oxide dispersoids such as Al2O3 i Y2O3 are much more stable even up to temperature of 1200°C than precipitates such as carbides or intermetallic phases [5÷9]. However, Vardavoulias et al. [10] were studied the influence of Al2O3 and Y2O3 (5 wt. %) ceramics and two different sintering activators BN and B2Cr (1 or 2 wt. %) on the tribological properties the AISI 304L and ALSI 316L stainless steel. The materials were received by the free sintering process in vacuum at temperature of 1250°C, where the duration of the process was 30 min. Wear tests were carried out using pin-on-disc apparatus. The application of Y2O3 ceramic and B2Cr sintering activator gave the highest density of the composites. However, the presence of ceramic particles (Al2O3 and Y2O3) and sintering activators improved significantly t[...]

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