20.500.12556/RUL-191036 Termodinamična analiza in optimizacija homogenizacije zlitine AlMg6 Thermodynamic analysis and optimisation of homogenisation of AlMg6 alloy V magistrskem delu je bila preučena aluminijeva zlitina AlMg6, pri kateri neustrezna mikrostruktura po litju povzroča težave pri valjanju v vročem. Namen raziskave je bil identificirati faze v litem stanju, ovrednotiti vpliv časa homogenizacijskega žarjenja na njihovo raztapljanje ter določiti enostopenjski režim, ki bi lahko nadomestil obstoječi večstopenjski industrijski postopek. Fazna ravnotežja za dejansko sestavo zlitine s 6,16 mas. % Mg so bila izračunana s programskim orodjem Thermo-Calc. Izvedeni so bili trije tipi izračunov: izopletni fazni diagram, ravnotežni deleži faz v odvisnosti od temperature in Scheilov izračun neravnotežnega strjevanja. Vzorci s petih mest prečnega prereza industrijsko ulite brame so bili žarjeni pri 540 °C od 4 do 14 h in gašeni v vodi, nato pa analizirani z diferenčno vrstično kalorimetrijo (DSC) ter s svetlobno in vrstično elektronsko mikroskopijo z energijsko disperzijsko spektroskopijo. Scheilov izračun je napovedal nastanek β-faze (Al3Mg2) ob koncu strjevanja pri neravnotežni temperaturi solidus 449,6 °C, kar se je ujemalo z endotermnim učinkom pri 448–451 °C na DSC ogrevnih krivuljah litih vzorcev. Po homogenizaciji tega učinka ni bilo več zaznati, razen pri enem robnem vzorcu po 6 h. Temperatura začetka glavnega talilnega vrha se je po homogenizaciji zvišala s 553–555 °C na 562–570 °C, površinski delež intermetalnih faz pa se je pri daljših časih znižal do 0,6 %. Fazi Al13Fe4 in Mg2Si sta skladno z izračuni ostali prisotni tudi po 14 h. Kot najustreznejša je bila predlagana enostopenjska homogenizacija pri 540 °C s trajanjem 8 h; teoretično bi zadoščalo že 6 h, vendar daljši čas zagotavlja zanesljivejšo raztopitev β-faze po celotnem prerezu brame. This master’s thesis investigates the aluminium alloy AlMg6, whose unfavourable as-cast microstructure causes difficulties during hot rolling. The aim was to identify the phases present in the as-cast state, to evaluate the effect of homogenisation time on their dissolution and to define a single-stage homogenisation regime that could replace the existing multi-stage industrial treatment. Phase equilibria for the actual alloy composition containing 6.16 wt.% Mg were calculated with the Thermo-Calc software. Three types of calculations were performed: an isopleth section, equilibrium phase fractions as a function of temperature and a Scheil calculation of non-equilibrium solidification. Samples taken from five positions across the cross-section of an industrially cast slab were annealed at 540 °C for 4 to 14 h, quenched in water and examined by differential scanning calorimetry, as well as by light and scanning electron microscopy with energy-dispersive X-ray spectroscopy. The Scheil calculation predicted the formation of the β phase (Al3Mg2) at the end of solidification at the non-equilibrium solidus temperature of 449.6 °C, which was consistent with an endothermic effect at 448–451 °C on the heating curves of the as-cast samples. After homogenisation, this effect was no longer detected, except in one edge sample after 6 h. Following homogenisation, the onset of the main melting peak increased from 553–555 °C to 562–570 °C, and the area fraction of intermetallic phases decreased to 0.6 % after longer annealing times. In agreement with the calculations, the Al13Fe4 and Mg2Si phases remained present even after 14 h. Single-stage homogenisation at 540 °C for 8 h is proposed as the most suitable regime; 6 h would theoretically be sufficient, but the longer time ensures more reliable dissolution of the β phase across the entire slab cross-section. aluminijeva zlitina AlMg6 homogenizacijsko žarjenje β-faza termodinamski izračuni diferenčna vrstična kalorimetrija mikrostruktura AlMg6 aluminium alloy homogenisation annealing β phase thermodynamic calculations differential scanning calorimetry microstructure true false false Slovenski jezik Angleški jezik Magistrsko delo/naloga 2026-11-11 09:00:10 2026-11-11 09:00:33 2026-11-12 04:12:26 0000-00-00 00:00:00 2026 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 1970-01-01 121425 32206.pdf 32206.pdf 1 9F0C9CB3467908CBCAACF965CFB738FA d72138e7a89828ace856c2817fa1841a1c45938dfefb61383ba0e0649b0084f6 e0ffca42-dda5-11f1-aea2-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=252902 Naravoslovnotehniška fakulteta 0 0 0