The application of innovative processing techniques to conventional raw materials can lead to new structural materials with specific mechanical and physical properties, which open up new possibilities of use in some areas of industry. The processing is enabled by powder metallurgy, which utilizes powders consisting of a metal matrix with dispersed stable particles achieved by mechanical alloying and their hot consolidation by rolling. New oxide dispersion strengthened (ODS) Fe-Al-based alloys are tested under different single and multiple thermomechanical treatments at different temperatures. The results show that new ODS alloys are significantly affected by the thermo-mechanical treatment, leading to microstructural changes. Their analysis is performed using different analytical methods such as optical microscopy, scanning electron microscopy and X-ray diffraction analysis. Keywords: ODS alloys, composite, steel, Fe-Al Uporaba inovativnih tehnik preoblikovanja na obi~ajnih materialih lahko privede do novih konstrukcijskih materialov s specifi~nimi mehanskimi in fizikalnimi lastnostmi, ki odpirajo nove mo`nosti uporabe v industriji. Metalurgija prahov omogo~a uporabo prahov s kovinsko osnovo z dispergiranimi stabilnimi delci, ki jih dobimo pri mehanskem legiranju in vro~i konsolidaciji z valjanjem. Nove zlitine Fe-Al, disperzijsko utrjene z oksidi (ODS), so bile preizku{ene pri razli~ni, eno-ali ve~stopenjski obdelavi pri razli~nih temperaturah. Rezultati ka`ejo, da ima termomehanska obdelava novih ODS zlitin mo~an vpliv, ki se vidi v spremembah mikrostrukture. Analiza je bila izvedena s pomo~jo razli~nih analitskih metod, kot so: svetlobna mikroskopija, vrsti~na elektronska mikroskopija in rentgenska difrakcijska analiza.
Titanium and its alloys are frequently used in many sectors, including the health care sector, where they outperform other materials. From the biocompatibility viewpoint, the preferred condition of these materials is ultrafine or nanostructured state. Processes based on severe plastic deformation (SPD) that are capable of producing microstructures with sizes of the order of nanometers are gaining importance these days. Their typical limitation is the small volume of material processed. One of available ways to enhancing the productivity is to combine the CONFORM continuous extrusion process with the ECAP method. This paper describes initial experience with this combined process in the CONFORM 315i machine, which is equipped with a specially-designed forming die chamber. Influence the number of passes through CONFORM machine on thermal stability was study by horizontal dilatometer and heat-flux calorimeter. The impact of deformation on the shift in recrystallization temperature of pure titanium was confirmed. The microstructure evolution and the grain growth behavior were investigated by electron back scattered diffraction (EBSD) technique. The deformed UFG titanium was annealed at a range of temperature (400-600 °C) for up to 6 h. The grain growth kinetics was characterized by calculating the grain growth activation energy Q and the time exponent n based on the experimental results for deformed material. Data for annealing temperatures of 550 and 600 °C allowed the values of the time exponent n = 0.19 and activation energy Q = 248 kJ/mol were calculated.
SPD (severe plastic deformation) processing of materials provides a great potential associated with the enhancement of their properties by refining the initial grain structure. The present experiments involved mechanical working of commercial-purity titanium (Ti Grade 2) with the CONFORM SPD technique, which is one of the SPD methods, and with rotary swaging. The objective was to process the material at as low temperatures as possible in order to avoid softening processes and, therefore, to achieve the maximum strengthening through a microstructure refinement. Three passes through a CONFORM SPD machine were completed and the resulting ultimate strength was 673 MPa. The average grain size was 330 nm. The greatest improvement of the mechanical properties was achieved in the first pass. In the subsequent passes, the contributions were minor. The processing in the CONFORM SPD machine did not impair the ductility of the material. Subsequently, the wires were rotary swaged. The ultimate strength achieved was 1070 MPa. The response of the properties to this forming method was markedly different. The reason is that rotary swaging does not belong to SPD techniques. It causes rapid work hardening and reduces the ductility of the material. The workpiece was subsequently investigated with the aid of several techniques. Light and transmission electron microscopy and X-ray diffraction were employed for evaluating the grain size, distribution and orientation. Keywords: equal-channel angular pressing, CONFORM SPD technique, rotary swaging, titanium, extrusion Velika plasti~na deformacija (angl. SPD) pri obdelavi materialov omogo~a veliko mo`nosti, povezane z izbolj{anjem njihovih lastnosti z izbolj{avo izvorne strukture zrn. Pri~ujo~i preizkus je vklju~eval mehansko obdelavo komercialno dostopnega~istega titana (Ti Grade 2) s CONFORM SPD-tehniko, ki je ena od SPD-metod, in s kovanjem. Namen je bil, da bi se material obdelalo pri~im ni`jih temperaturah, kot je mogo~e, da bi se izognili procesom meh~anja in, da bi dosegli maksimalno krepitev s prei{~enjem strukture. Narejeni so bili trije nizi v CONFORM SPD-stroju in kon~na mo~je dosegla 673 MPa. Povpre~na velikost zrn je bila 330 nm. Najve~je izbolj{ave mehanskih lastnosti so bile dose`ene v prvem nizu. V slede~ih nizih so bile le-te manj{e. Obdelava v CONFORM SPD-stroju ni {kodovala duktilnosti materiala. Posledi~no so bile`ice zvite. Kon~na mo~je bila 1070 MPa. Odziv lastnosti na to metodo oblikovanja je bil izrazito druga~en. Razlog je v tem, da rotacijsko zvijanje ne sodi v tehnike SPD. Rotacijsko zvijanje povzro~i hitro utrjevanje in zmanj{uje duktilnost materiala. Vzorec je bil nato raziskan s pomo~jo vet ehnik. Za ovrednotenje velikosti, razporeditve in orientacije zrn, sta bili uporabljeni transmisijska elektronska mikroskopija in rentgenska difrakcija.
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