Sinteza in mehanska karakterizacija zlitin iz sistema Al-Mn utrjenih s kvazikristali : doktorska disertacija

Zaky, Adam (avtor), Markoli, Boštjan (mentor)

Disertacija je obsegala sintezo, karakterizacijo, toplotno obdelavo in opredelitev mehanskih lastnosti aluminijeve kvazikristalne zlitine iz sistema Al-Mn-Si-Cu-Mg. Izdelali smo zlitino z velikim deležem primarne ikozaedrične kvazikristalne faze IQC in majhnim deležem njej konkurenčne faze ß-AlMnSi. Postopek izdelave je temeljil na gravitacijskem litju v bakreno kokilo. Raziskanih je bilo večje število zlitin različnih sestav. Največji potencial za nadaljnje preiskave je izkazala zlitina, ki je vsebovala poleg aluminija še 4,00 at. % Mn, 1,50 at. % Si in Cu ter 3,75 at. % Mg. Z namenom dodatnega povečanja deleža primarne faze IQC smo zlitinam dodali komercialna inokulanta TiC in TiB2. Največje deleže primarne faze IQC smo dosegli z uporabo 0,0150 mas. % TiC. Pri dodatku 0,0224 mas. % TiC je povečanje njenega deleža spremljalo tudi povečanje deleža faze ß-AlMnSi. Vpliv različnih sestav in deležev inokulanta na mikrostrukturo smo zasledovali s pomočjo svetlobne in elektronske mikroskopije. Deleže primarne faze IQC in faze ß-AlMnSi smo ugotavljali s pomočjo mikrostrukturne segmentacije, ki je temeljila na tehniki strojnega učenja s prepoznavanjem karakteristične morfologije faz. Za ta namen sta bila uporabljena odprtokodna programa ilastik in FIJI. V doktorskem delu smo raziskovali tudi vpliv toplotnih obdelav po postopkih T5 in T6 na procese razmešanja v trdnem in posledično na trdoto. Izvedli smo enourna in štiriindvajseturna žarjenja pri povišanih temperaturah z namenom ugotavljanja temperaturne stabilnosti faze IQC. Spremembe med žarjenjem smo zasledovali s pomočjo tehnik rentgenske fazne analize in uklona povratno sipanih elektronov ter vrstične elektronske mikroskopije. Trdote faze ?Al po T5 in T6 obdelavi smo izmerili z Vickersovo metodo. S pomočjo presevne elektronske mikroskopije smo na nano-nivoju zasledovali procese razmešanja v trdnem. V vzorcu T5 smo odkrili prisotnost izločkov Al2CuMg. V vzorcu T6 pa, poleg prej omenjenih, še disperzoide faze T. Natezni preizkusi so bili opravljeni na zlitini AlMn4Si1,5Cu1,5Mg3,75 z različnimi deleži TiC. Najboljšo kombinacijo natezne trdnosti in celotnega raztezka smo dosegli z dodatkom 0,0150 mas. % TiC, najslabšo pa z dodatkom 0,0224 mas. % TiC.

• Jezik: Slovenski jezik
• Ključne besede: aluminijeva kvazikristalna zlitina, mikrostrukturna segmentacija, odprtokodni program za strojno učenje, mehanske lastnosti, toplotne obdelave
• Vrsta gradiva: Doktorsko delo/naloga
• Tipologija: 2.08 - Doktorska disertacija
• Organizacija: NTF - Naravoslovnotehniška fakulteta
• Kraj izida: Ljubljana
• Založnik: A. Zaky
• Leto izida: 2025
• Št. strani: XXI, 139 str.
• PID: 20.500.12556/RUL-171103
• UDK: 669
• COBISS.SI-ID: 245503747
• Datum objave v RUL: 05.08.2025

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Synthesis and mechanical characterization of Al-Mn alloys reinforced with quasicrystals : ph. d. thesis

Izvleček

The work comprised of the synthesis, characterization, heat treatment and mechanical properties evaluation of an aluminium quasicrystaline alloy from the system Al-Mn-Si-Cu-Mg. Our main objective was to produce an alloy with a high proportion of primary icosahedral phase IQC and a low proportion of competing β-AlMnSi. The synthesis was carried out by gravity casting into a copper mould. Several alloys with different compositions were investigated. The alloy with 4.00 at. % Mn, 1.50 at. % Si and Cu and 3.75 at. % Mg showed the highest potential for further investigation. Different additions of TiC and TiB2 were introduced into the melt to further increase the proportion of the primary IQC phase. The highest phase fraction was achieved with the addition of 0.0150 wt.% TiC. With the addition of 0.0224 wt.% TiC, the increase in the primary IQC phase was accompanied by an increase in the β-AlMnSi phase. The effects of chemical composition and additives on the microstructure were investigated by optical and electron microscopy. Fractions of the primary IQC and β-AlMnSi phase were determined using machine learning to segment the microstructure based on phase morphology, for which open-source software ilastik and FIJI were used. T5 and T6 heat treatments were performed to investigate their influence on the solid solution diffusion processes and alloy hardness. Hourly and twenty-four-hour anneals were performed at elevated temperatures to determine the thermal stability of the IQC phase. The analyses were carried out using X-ray diffraction, backscattered electron diffraction and electron microscopy. The hardness of the αAl phase was measured using the Vickers method. The use of a transmission electron microscope allowed us to investigate the influence of tempering on the solid solution diffusion processes on the nanoscale. Precipitates of Al2CuMg were observed in T5 and T6 samples. Dispersoids of the T-phase were also observed in the latter. Tensile tests were performed on the alloy AlMn4Si1,5Cu1,5Mg3,75 with different TiC additions. The best combination of tensile strength and total elongation was achieved with 0.0150 wt.% TiC. Alloys with 0.0224 wt.% TiC performed the worst.

• Ključne besede: aluminium quasicrystaline alloy, microstructural segmentation, open-source machine learning software, mechanical properties, heat treatments