Termodinamična karakterizacija zlitine Al-Ca-Li : diplomsko delo

Polajžar, Rene (author), Medved, Jožef (mentor)

Aluminij je najpomembnejša neželezna kovina moderne dobe. Lastnosti njegovih zlitin so odvisne od njihove sestave in mikrostrukture. Z dodanimi legirnimi elementi mu močno povečamo uporabnost. Razdelimo ga v več skupin, ki so ločene po glavnih legirnih elementih. Kovine z nizko gostoto, kot sta litij in kalcij, se dodajata aluminiju za zmanjšanje njegove gostote in povečanje trdnosti zlitine. Zaradi hitrega razvoja kovinskih materialov in aplikacij so potrebne raziskave novih naprednih zlitin z boljšimi mehanskimi lastnostmi. V diplomskem delu smo termodinamično karakterizirali zlitino iz sistema Al-Ca-Li. Najprej smo izdelali zlitino tako, da smo tehnično čistemu aluminiju legirali litij in kalcij, nato pa vse skupaj ulili v jekleno merilno celico in izvedli enostavno termično analizo, z ohlajevalne krivulje smo odčitali likvidus temperaturo, solidus temperaturo in dve evtektski temperaturi. Nadaljevali smo z analizo sestave zlitine s pomočjo rentgenske fluorescenčne analize. Izvedli smo diferenčno vrstično kalorimetrijo pri kateri smo opredelili talilno in strjevalno entalpijo prisotnih faz in karakterističnih temperatur taljenja/strjevanja. Izvedli smo tudi termodinamični izračun za prikaz izopletnih ravnotežnih faznih diagramov in Scheilovih diagramov. Vzorec smo opazovali pod elektronskim mikroskopom in definirali faze v izdelanih zlitinah. Rezultati so prikazali, da je kalcij z aluminijem tvoril evtektik (?-Al + Al4Ca), pokazali pa so tudi, da se je aluminij povezal z železom in tvoril evtektsko fazo Al13Fe4.

• Language: Slovenian
• Keywords: zlitine Al-Ca-Li, termodinamično modeliranje, enostavna termična analiza, diferenčna vrstična kalorimetrija
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Place of publishing: Ljubljana
• Publisher: R. Polajžar
• Year: 2024
• Number of pages: XI, 24 f.
• PID: 20.500.12556/RUL-161719
• UDC: 669
• COBISS.SI-ID: 212468483
• Publication date in RUL: 13.09.2024

POLAJŽAR, Rene, 2024, Termodinamična karakterizacija zlitine Al-Ca-Li : diplomsko delo [online]. Bachelor’s thesis. Ljubljana : R. Polajžar. [Accessed 1 April 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=161719

Secondary language

• Language: English
• Title: Thermodynamic characterization of Al-Ca-Li alloy : diploma work

Abstract

Aluminum is the most important non-ferrous metal of the modern age. The properties of its alloys depend on their composition and microstructure. By adding alloying elements, we can significantly enhance the usability of aluminum. It is categorized into several groups based on the main alloying elements. Metals with low density, such as lithium and calcium, are added to aluminum to reduce its density and increase the strength of the alloy. Due to the rapid development of metallic materials and applications, there is a need to research new advanced alloys with better mechanical properties. In this thesis, we thermodynamically characterized an Al-Ca-Li alloy system. First, we prepared the alloy by alloying technically pure aluminum with lithium and calcium, then cast it into a steel measurement cell and performed a simple thermal analysis. From the cooling curve, we determined the liquidus temperature, solidus temperature, and two eutectic temperatures. We then continued with the determination of the alloy composition using X-ray fluorescence analysis. Differential scanning calorimetry was conducted to determine the melting and solidification enthalpies of the present phases and characteristic temperatures. Thermodynamic calculations were also performed to illustrate isopleth diagrams and Scheil diagrams. The sample was observed using an electron microscope to define the phases in the alloys. The results showed that calcium formed an eutectic (α-Al + Al4Ca) with aluminum and also indicated that aluminum combined with iron to form a phase Al13Fe4.

• Keywords: Al-Ca-Li alloys, thermodynamic modeling, simple thermal analysis, differential scanning calorimetry