Hitro strjene zlitine vrste Al-Ni-La : diplomsko delo

Švegl, Lovrenc (avtor), Bizjak, Milan (mentor)

V tem diplomskem delu smo obravnavali hitro strjeno zlitino tipa Al-Ni-La. Zastavljen cilj te naloge je bil uspešna izdelava zlitine in nadaljnja analiza le te s pomočjo različnih metod, da lahko ustrezno preučimo mikrostrukturo in določimo pomembne temperature pri katerih se zgodijo mikrostrukturne spremebe v materialu. Zlitino smo pripravili in izdelali na napravi za hitro strjevanje na vrtečem se valju, ki je nameščena na Oddelku za materiale in metalurgijo – OMM. Izdelek, ki smo ga dobili so bili tanki kovinski trakovi. Te smo po ohladitvi na sobno temperaturo najprej analizirali na napravi za merjenje električne upornosti. Na podlagi dobljenih rezultatov smo lahko predpostavili pomembne temperature pri katerih prihaja do mikrostrukturnih sprememb med segrevanjem in ohlajanjem. Nadaljnje analize, katere so pripomogle k bolj natančnim predpostavkam o lastnostih zlitine so obsegale analizo mikrostrukture in kemijske sestave posameznih faz. To smo izvedli s pomočjo vrstične elektronske mikroskopije (SEM) ter termične diferenčne dinamične kalorimetrije (DSC), pri kateri smo vzorce segrevali do značilnih, z elektrometrijo določenih temperatur, pri katerih se zgodijo določene mikrostrukturne spremembe. Ugotovili smo, da dobimo s hitrim strjevanjem zlitine Al-Ni-La edinstvene mikrostrukture, ki jih pri drugih postopkih ni mogoče zaslediti. Predvsem je zanimiva kristalizacija določenih faz v obliki celične mikrostrukture v podpovršinskem področju traku, ki ni bil v stiku z valjem in ima zato nekoliko nižjo hitrost ohlajanja in strjevanja, ter nano celični mikrostrukturi v spodnjem delu traku, ki je bil v stiku z valjem. Po segrevanju zlitine v specifično temperaturno območje, ki smo ga določili s pomočjo elektrometrije, nismo zaznali bistvenih sprememb v mikrostrukturi. Opaznen je bil razpad celične mikrostrukture in nastanek globularnih delcev.

• Jezik: Slovenski jezik
• Ključne besede: hitro strjevanje, Al-Ni-La zlitine, mikrostruktura, melt spinning
• Vrsta gradiva: Diplomsko delo/naloga
• Tipologija: 2.11 - Diplomsko delo
• Organizacija: NTF - Naravoslovnotehniška fakulteta
• Kraj izida: Ljubljana
• Založnik: [L. Švegl]
• Leto izida: 2021
• Št. strani: XIII, 38 f.
• PID: 20.500.12556/RUL-131170
• UDK: 669
• COBISS.SI-ID: 85679619
• Datum objave v RUL: 23.09.2021

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Rapid solidification of Al-Ni-La alloys : diploma work

Izvleček

In this diploma work we produced and analysed rapid solidified Al-Ni-La alloy. Our goal was successful production of ribbons and their further analysis with different research methods, so we could determine microstructure and important temperatures where microstructural changes occur. We produced our alloy on melt spinner machine located at Department of Materials and Metallurgy – OMM. Product that we got were thin metal ribbons. After solidification those were analysed on machine for measuring electrical resistance. Based on the results of these measurements we could predict important temperatures where microstructural changes occur. Further analysis, that helped us to predict alloy properties even better, was analysis of microstructure. That was done on scanning electron microscope (SEM) where we also did chemical analysis of our samples. We also did thermal analysis with measurements of differential scanning calorimetry (DSC). After we finished with analysis on our sample, we heated alloy ribbons to temperatures that we predetermined with measurements of resistance so we could then see what microstructural changes occurred at this temperature interval. Results of our analysis showed that we can obtain specific microstructure with rapid solidification on melt spinner, that can not be obtained by any other solidification method. Here we speak about cellular microstructure, that can be found in the upper part of ribbons under the surface. In the lower part of ribbon which was near contact with the surface area of a cylinder we obtained nano cellular microstructure. We aged our alloy into specific temperature ranges, in which some microstructural changes should happen, because on charts for electrical resistance we detected here some changes in its derivation. There were only minor changes in microstructure at those temperatures. We discovered that the cellular microstructure was decomposed and some globular particles were formed.

• Ključne besede: rapid solidification, Al-Ni-La alloys, microstructure, melt spinning