Spremljanje staranja zllitine EN AW2011 z meritvijo električne upornosti : diplomsko delo

Pesek, Sara (author), Medved, Jožef (mentor)

Zlitina EN AW2011 je aluminijeva zlitina, ki spada v skupino 2XXX, kjer je aluminiju dodanih 5 – 6 mas. % Cu. Zlitine iz te skupine, za razliko od drugih aluminijevih zlitin, so slabo korozijsko odporne, zato jih je potrebno zaščititi s premazi ali z anodiziranjem. Z dodatkom bakra se materialu bistveno poveča trdnost, zato se zlitine skupine 2XXX uporabljajo v letalski in vesoljski tehnologiji. Poznamo različne načine toplotne obdelave, najpogostejša sta raztopno žarjenje in staranje. Pri postopku žarjenja segrejemo vzorec do določene temperature in ga na tej temperaturi zadržimo nekaj časa, nato pa ohladimo. Staranje pa je postopek, pri katerem se iz prenasičene trdne raztopine izločijo delci, ki lahko močno povečajo trdnostne lastnosti. Električna upornost aluminija je zelo nizka, saj je material s četrto najnižjo upornostjo. Na njegovo specifično električno upornost vpliva količina in oblika prisotnih legirnih elementov ter nečistoč v mikrostrukturi. Aluminijeve zlitine imajo večji delež tujih atomov, zato imajo višjo električno upornost kot čisti aluminij. Namen diplomskega dela je bil spremljati staranje zlitine EN AW2011 z meritvijo električne upornosti. Zlitino EN AW2011 smo najprej homogenizirali, nato pa umetno starali in rezultate spremljali preko meritev specifične električne upornosti. Z namenom primerjalne analize smo 12 h staranje izvajali pri dveh temperaturah in sicer 150 °C ter 180 °C ter izvedli DSC analizo. Izdelali smo krivulje poteka staranja v odvisnosti od časa. Ob analizi krivulj lahko zaključimo, da osnovni procesi staranja zlitine EN AW2011 pri 150 oC potečejo v prvih sedmih urah, za tem se krivulja izravna.

• Language: Slovenian
• Keywords: zlitina EN AW2011, staranje, specifična električna upornost, DSC
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Place of publishing: Ljubljana
• Publisher: [S. pesek]
• Year: 2022
• Number of pages: XI, 38 f.
• PID: 20.500.12556/RUL-141502
• UDC: 669.187.25(043.2)
• COBISS.SI-ID: 130447363
• Publication date in RUL: 30.09.2022

PESEK, Sara, 2022, Spremljanje staranja zllitine EN AW2011 z meritvijo električne upornosti : diplomsko delo [online]. Bachelor’s thesis. Ljubljana : S. pesek. [Accessed 30 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=141502

Secondary language

• Language: English
• Title: Monitoring the aging of alloy EN AW2011 by measuring electrical resistance : diploma work

Abstract

Alloy EN AW2011 is an aluminum alloy that belongs to the series of alloys 2XXX, where 5 - 6 wt.% Cu is added to aluminum. Alloys from this group, unlike other aluminum alloys, are poorly corrosion resistant, so they need to be protected by coatings or anodizing. The addition of copper significantly increases the strength of the material, so 2XXX series alloys are used in aerospace technology. Different methods of heat treatment are known, the most common are solution annealing and aging. In the annealing process, the sample is heated to a certain temperature, and it is hold at the same temperature for a while, then it is cooled. Aging is a process in which particles are precipitated from solid solutions, which can greatly increase the strength properties. The electrical resistance of aluminum is very low, as it is the material with the fourth lowest electric resistivity. Its specific electrical resistance is influenced by the amount and shape of the alloying elements and the impurities present in the microstructure. Aluminum alloys have a higher amount of alloying atoms, so they have a higher electrical resistivity than pure aluminum. The purpose of bachelor thesis was to monitor the aging process of the EN AW2011 alloy by measuring the electrical resistivity. The alloy EN AW2011 was first homogenized, then artificially aged and the results were monitored through measurements of specific electrical resistivity. For the purpose of comparative analysis, 12-hour aging was performed at two temperatures, 150 ° C and 180 ° C. Afterwards, the DSC analysis was performed and the curves of the aging process as a function of time were created. Analyzing the curves, we can conclude that the basic aging process of the alloy EN AW2011 at 150 ºC takes place in the first seven hours, after which the curve is smoothed.

• Keywords: EN AW2011 alloy, aging, specific electric resistance, DSC