20.500.12556/DKUM-92786 Mikrostruktura in lastnosti zlitin na osnovi Al-Mn-Cu, obdelanih s trenjem in mešanjem doktorska disertacija Microstructure and properties of friction stir processed Al-Mn-Cu-based alloys V doktorskem delu so bile raziskane mikrostrukture in lastnosti dveh zlitin iz sistema Al-Mn-Cu, obdelanih s trenjem in mešanjem (FSP) in varjenih s trenjem in mešanjem ( FSW), ki imata v mikrostrukturi ali kvazikristalne faze, ki so nastale pri strjevanju, ali mešanico kvazikristalnih in L12-Al3X izločkov, ki nastanejo pri umetnem staranju. Z visokohitrostnnim dvovaljnim litjem zlitine Al94Mn2Cu2Be smo uspešno izdelali lite trakove, pri katerem v mikrostrukturi nastane v meddendritnem prostoru kvazikristalni evtektik. Primarni delci kvazikristalnega aproksimanta Al15Mn3Be2 so nakopičeni predvsem v sredini traku in s tem zmanjšajo žilavost zlitine. Mikrostrukturo zlitine sestavlja -Al, ikozaedrični kvazikristal IQC, θ-Al2Cu, Be4Al (Mn, Cu) in Al15Mn3Be2. Obdelava s trenjem in mešanjem FSP je močno spremenila mikrostrukturo zlitine Al94Mn2Cu2Be2 v območju mešanja. Veliki primarni delci Al15Mn3Be2 in kvazikristalni evtektik so se zdrobili in pretvorili v stabilno fazo 1-Al29Mn6Cu4. Večji vnos energije pri FSP in FSW je privedel do zmanjšanja trdote v območju mešanja, povečala se je natezna trdnost, udarna žilavost, kritične vrednosti lomne žilavosti JIC in KJIC ter odpornost proti napredovanju razpoke. Zlitina Al-Mn-Cu, mikrolegirana z elementi Be, Sc, Zr, Cr in V, označena z AlMnCu(M), je bila po litju v bakreno kokilo obdelana s FSP. Lite plošče smo varili med seboj in s komercialno zlitino EN AW 6082 s trenjem in mešanjem FSW. Največji delež v zlitini Al-Mn-Cu(M) je zavzemala faza α-Al. V meddendritnih prostorih so bile po litju identificirane faze Al4Mn, θ-Al2Cu, IQC in Al2Cu(Sc). Po toplotni obdelavi so nastali trije tipi izločkov: ikozaedrični kvazikristalni, dekagonalni kvazikristalni in L12-Al3(Sc, Zr). Toplotna obdelava je bistveno povečala trdoto in povzročila, da je bilo območje mešanja po FSP v toplotnoobdelanih vzorcih manjše kot v litih vzorcih. Trdota v območju mešanja se je zmanjševala z večjim vnosom energije. V območju mešanja je bila drobna disperzija faze τ1- Al29Mn6Cu4. Mikrolegirana zlitina Al-Mn-Cu(M) se je uspešno varila z zlitino EN AW 6082 v stanju T6. Območje mešanja je bilo nesimetrično in bolj pomaknjeno v zlitino EN AW 6082. Pri intenzivnejšem mešanju se je povečala trdota v območju mešanja. The doctoral thesis investigates the microstructures and properties of two alloys from the Al-Mn-Cu system, processed by Friction Stir Processing (FSP) and Friction Stir Welding (FSW). These alloys contain either quasicrystalline phases formed during solidification or a mixture of quasicrystalline and L12-Al3X precipitates formed during artificial aging. Using high-speed twin-roll casting, strips of the Al94Mn2Cu2Be2 alloy were successfully produced. In their microstructure, a quasicrystalline eutectic formed in the interdendritic space. Primary particles of the quasicrystal approximant Al15Mn3Be2 accumulated mostly in the center of the strip, which reduced the alloy's toughness. The microstructure consists of α-Al, icosahedral quasicrystal (IQC), θ-Al₂Cu, Be₄Al(Mn,Cu), and Al15Mn3Be2. Friction Stir Processing (FSP) significantly altered the microstructure of the Al94Mn2Cu2Be2 alloy in the stirred zone. Large primary Al15Mn3Be2 particles and quasicrystalline eutectic were fragmented and transformed into the stable t1-Al29Mn6Cu4 phase. The higher energy input from FSP and FSW led to reduced hardness in the stirred zone, while tensile strength, impact toughness, critical fracture toughness values JIC and KJIC, and resistance to crack propagation all increased. The Al-Mn-Cu alloy microalloyed with Be, Sc, Zr, Cr, and V, designated AlMnCu(M), was cast into a copper mold and processed using FSP. Cast plates were welded together and with the commercial alloy EN AW 6082 using FSW. The α-Al phase was the dominant phase in the Al-Mn-Cu(M) alloy. In the interdendritic areas after casting, phases Al4Mn, θ-Al2Cu, IQC, and Al2Cu(Sc) were identified. After heat treatment, three types of precipitates formed: icosahedral quasicrystalline, decagonal quasicrystalline, and L12-Al3(Sc, Zr). Heat treatment significantly increased hardness and reduced the size of the stirred zone in heat-treated samples compared to as-cast samples. Hardness in the stirred zone decreased with increased energy input. A fine dispersion of the τ1- Al29Mn6Cu4 phase was present in the stirred zone. The microalloyed Al-Mn-Cu(M) alloy was successfully welded with EN AW 6082-T6. The stirred zone was asymmetric and more shifted into the EN AW 6082 alloy. With more intense stirring, the hardness in the stirred zone increased. aluminijeve zlitine kvazikristali mikrostruktura obdelava in varjenje s trenjem in mešanjem mehanske lastnosti aluminum alloys quasicrystals microstructure friction stir processing and welding mechanical properties true true false [M. Macerl] Slovenski jezik Angleški jezik Doktorsko delo/naloga 2025-05-13 13:26:44 2025-11-19 09:00:58 2025-11-26 03:11:02 0000-00-00 00:00:00 2025 0 Maribor 0 Maribor XXI, 143 str. 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 620.17/.18:669.715(043.3) 258675459 DOK_Macerl_Matjaz_2025.pdf DOK_Macerl_Matjaz_2025.pdf 1 02515F3D1A290B95BED4CB9DC0C0692B 0cc75a4e7327b756c7f76b5bc809128ec034debe44217988a9d1664d2c88e97e 7994f22a-c51a-11f0-865f-00155d000105 https://dk.um.si/Dokument.php?lang=slv&id=200757 Fakulteta za strojništvo 0 0 0