Detekcija mikrostrukturnih sprememb z meritvami električne upornosti : diplomsko delo

Tič, Filip (author), Bizjak, Milan (mentor)

V tem diplomskem delu sta predstavljeni sinteza in karakterizacija hitro strjene zlitine Al-Fe-Si-Zr. Hitro strjene trakove zlitine smo izdelali na napravi za hitro strjevanje na vrtečem se valju. Z uporabo vrstične elektronske mikroskopije in sprotnega merjenja električne upornosti smo določili kinetiko in zaporedje mikrostrukturnih sprememb med segrevanjem trakov s konstantno hitrostjo 5 °C/min. Mikrostruktura hitro strjenih trakov zlitine je celična. Celična morfologija strjevanja se spreminja z oddaljenostjo od spodnje k zgornji prosti površini. Na spodnji strani traku, ki je bil v kontaktu z valjem je nastala nanocelična, na gornjem delu traku pa celična in/ali dendritna mikrostruktura. Primarna faza ?-Al predstavlja notranjost celic. Stene celic, ki tvorijo kontinuirno mrežo, pripadajo fazi bogati na Al, Fe, Si. S sprotno meritvijo električne upornosti in z elektronsko mikroskopijo smo zaznali in analizirali mikrostrukturne spremembe nastale med segrevanjem. Pri meritvah električne upornosti smo zaznali dva temperaturna intervala sprememb. Največja mikrostrukturna sprememba, ki je nastala po segrevanju preko prvega temperaturnega intervala, je razgradnja celične mikrostrukture. Pri segrevanju preko drugega temperaturnega intervala sprememb pa poteka proces rasti in preoblikovanja delcev v matrici ?-Al. Proces mikrostrukturnih sprememb je relativno zapleten in poteka preko vmesnih metastabilnih faz.

• Language: Slovenian
• Keywords: Al-Fe-Si-Zr zlitine, melt spinning, hitro strjevanje, mikrostruktura, električna upornost
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Place of publishing: Ljubljana
• Publisher: [F. Tič]
• Year: 2022
• Number of pages: XII, 36 f.
• PID: 20.500.12556/RUL-138702
• UDC: 669
• COBISS.SI-ID: 127186179
• Publication date in RUL: 10.08.2022

TIČ, Filip, 2022, Detekcija mikrostrukturnih sprememb z meritvami električne upornosti : diplomsko delo [online]. Bachelor’s thesis. Ljubljana : F. Tič. [Accessed 22 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=138702

Secondary language

• Language: English
• Title: The detection of microstructural changes with electrical resistance measurements : diploma work

Abstract

In this work, the synthesis and characterization of a rapidly solidified Al-Fe-Si-Zr alloy is presented. The rapidly solidified alloy ribbons were prepared using a melt spinning machine. The kinetics and sequence of microstructural changes during heating of the ribbons at a constant rate of 5 ⁰C/min were determined by scanning electron microscopy as well as on-line electrical resistivity measurements. The microstructure of the rapidly solidified alloy ribbons is cellular. The cellular morphology of the solidification varies with the distance between the bottom surface and the top free surface. A nanocellular microstructure has formed on the bottom surface of the strip in contact with the roller, while a cellular and/or dendritic microstructure has formed on the top surface of the strip. The primary α-Al phase represents the interior of the cells. The cell walls, which form a continuous network, belong to the Al, Fe, and Si reach phases. The microstructural changes occurring during heating were detected and analysed by on-line electrical resistance measurements and electron microscopy. Two temperature intervals of changes were detected in the electrical resistivity measurements. The main microstructural change that occurred after heating beyond the first temperature interval was the deterioration of the cell structure. However, when heating beyond the second temperature interval, a process of growth and reshaping of particles in the α-Al matrix takes place. The process of microstructural change is relatively complex and occurs via intermediate metastable phases.

• Keywords: Al-Fe-Si-Zr alloy, melt spinning, rapid solidification, microstructure, electrical resistivity