Nemísitelné slitiny založené na systému Cu-Fe připravené metodami práškové metalurgie
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B
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Vysoké učení technické v Brně. Fakulta strojního inženýrství
Abstract
Cu-Fe systém s obmedzenou zmiešavateľnosťou sa často využíva na prípravu pokročilých heterogénnych zliatin. Uváženým výberom legujúcich prvkov je možné legovať jednotlivé fázy, a tým prispôsobovať mikroštruktúru a mechanické vlastnosti materiálu podľa potreby. Avšak na prípravu multikomponentných materiálov je potrebné plne porozumieť efektu jednotlivých legujúcich prvkov na mikroštruktúru a výsledné vlastnosti zliatin systému Cu-Fe. Napriek tomu, že najpoužívanejšou metódou výroby materiálov je odlievanie, mechanické legovanie sa ukazuje byť vhodnou alternatívou, zabezpečujúc navyše možnosť vytvorenia veľmi jemnej mikroštruktúry. Predkladaná bakalárska práca sa zameriava na charakteristiku Cu50Fe25Cr25 a Cu50Fe25Ni25 zliatin a vplyv legujúcich prvkov na ich mikroštruktúru. Cr a Ni boli vybraté ako prvky v zliatine podporujúce BCC a FCC fázu, v uvedenom poradí. Zliatiny boli pripravené mechanickým legovaním, s následnou konsolidáciou pomocou metódy Spark plasma sintering. Mikroštruktúra mletých práškov, rovnako ako aj konsolidovaných vzoriek, bola skúmaná, pričom bol vyhodnocovaný vplyv legujúcich prvkov na vývoj mikroštruktúry počas spekania. Taktiež bolo vykonané meranie tvrdosti konsolidovaných vzoriek. Počas mechanického legovania nebol dosiahnutý vznik presýteného tuhého roztoku v celom objeme zliatin, nakoľko tieto neboli jednofázové. Avšak, v oboch vzorkách sa presýtený tuhý roztok vytvoril aspoň čiastočne, a následne sa počas spekania rozpadol na multifázovú mikroštruktúru.
The immiscible Cu-Fe system is often used as a base for advanced heterogeneous alloys. With a suitable selection of alloying elements, it is possible to alloy individual phases and therefore tailor microstructure and final properties of a material as needed. To prepare the mentioned multicomponent alloys, it is necessary to understand the effect of individual alloying elements on the microstructure and properties of the Cu-Fe system. Although mostly used method in production of such materials is casting, mechanical alloying appears to be a suitable alternative, enabling a very fine microstructure to be created. The following bachelor´s thesis is focused on the characterization of Cu50Fe25Cr25 and Cu50Fe25Ni25 alloys and the effect of the alloying elements on their microstructure. Cr and Ni were selected as a BCC and FCC phase enhancing elements, respectively. The alloys were prepared by mechanical alloying using high-energy ball mill, with subsequent densification using spark plasma sintering. The microstructure of milled powders, as well as bulk samples, was examined, and the evolution of the microstructure during sintering evaluated with respect to the alloying elements. In addition, the hardness of bulk samples was measured. During the mechanical alloying a complete mixing was not achieved, as the milled powders were not single phase. However, a metastable FCC supersaturated solid solution was formed at least partially in both alloys, further decomposing into a multiphase microstructure after sintering.
The immiscible Cu-Fe system is often used as a base for advanced heterogeneous alloys. With a suitable selection of alloying elements, it is possible to alloy individual phases and therefore tailor microstructure and final properties of a material as needed. To prepare the mentioned multicomponent alloys, it is necessary to understand the effect of individual alloying elements on the microstructure and properties of the Cu-Fe system. Although mostly used method in production of such materials is casting, mechanical alloying appears to be a suitable alternative, enabling a very fine microstructure to be created. The following bachelor´s thesis is focused on the characterization of Cu50Fe25Cr25 and Cu50Fe25Ni25 alloys and the effect of the alloying elements on their microstructure. Cr and Ni were selected as a BCC and FCC phase enhancing elements, respectively. The alloys were prepared by mechanical alloying using high-energy ball mill, with subsequent densification using spark plasma sintering. The microstructure of milled powders, as well as bulk samples, was examined, and the evolution of the microstructure during sintering evaluated with respect to the alloying elements. In addition, the hardness of bulk samples was measured. During the mechanical alloying a complete mixing was not achieved, as the milled powders were not single phase. However, a metastable FCC supersaturated solid solution was formed at least partially in both alloys, further decomposing into a multiphase microstructure after sintering.
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Citation
LACOVÁ, A. Nemísitelné slitiny založené na systému Cu-Fe připravené metodami práškové metalurgie [online]. Brno: Vysoké učení technické v Brně. Fakulta strojního inženýrství. 2022.
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Document version
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sk
Study field
Základy strojního inženýrství
Comittee
doc. Ing. Vít Jan, Ph.D. (předseda)
doc. Ing. Bohumil Pacal, CSc. (místopředseda)
prof. Ing. Martin Trunec, Dr. (člen)
Ing. Libor Válka, CSc. (člen)
Ing. Martin Zelený, Ph.D. (člen)
Date of acceptance
2022-06-14
Defence
Studentka prezentovala svoji závěrečnou práci a odpověděla na otázky oponenta. Dále odpovídala na dotazy členů zkušební komise:
1) Jak je možné uvádět hodnotu tvrdosti u zkoušky podle VIckerse v MPa? - odpovězeno
2) Jaké mají prezentované slitiny praktické využití? - odpovězeno
Result of defence
práce byla úspěšně obhájena
Document licence
Standardní licenční smlouva - přístup k plnému textu bez omezení