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Title:Thermal stability of Al-Mn-Be melt-spun ribbons
Authors:Lojen, Gorazd (Author)
Bončina, Tonica (Author)
Zupanič, Franc (Author)
Files:.pdf Materiali_in_Tehnologije_2012_Lojen,_Boncina,_Zupanic_THERMAL_STABILITY_OF_Al-Mn-Be_MELT-SPUN_RIBBONS.pdf (777,98 KB)
MD5: 690600240120D1384439D82CE6FE6272
 
URL http://mit.imt.si/Revija/izvodi/mit124/lojen.pdf
 
Language:English
Work type:Scientific work (r2)
Typology:1.01 - Original Scientific Article
Organization:FS - Faculty of Mechanical Engineering
Abstract:As with other kinds of finely dispersed, small particles, icosahedral quasicrystals (IQCs) also have a distinct strengthening effect, which can be utilised to enhance the mechanical properties of aluminium alloys. In Al-Mn-Bealloys, IQCs already form at moderate cooling rates, which can be utilised when using some conventional casting processes, like mould or injection casting. In this case, however, crystalline intermetallic phases are also present and the mechanical properties are inferior to those of two-phase aAl-IQC alloys. Two-phase microstructures are feasible using rapid solidification techniques, e.g., melt spinning. Further processing often involves technologies (consolidation, extrusion etc.), which include the influence of heat. The alloy must not be overheated in order to preserve the strengthening effect of the metastable IQC-particles. In this investigation the Al-Mn-Be alloy was melt-spun using a free-jet melt spinner. Subsequently, the thermal stability of the IQCs was explored by annealing the ribbons for 24h at different temperatures. The samples were examined in the as-cast and heat-treated conditions using a dual-beam, scanning electron microscope (SEM-FIB), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It was discovered that in the as-cast condition, the ribbons had a two-phase microstructure, consisting of an aAl matrix and finely dispersed IQCs. During annealing at temperatures up to 400 °C, the IQCs did not decompose and the phase composition remained unchanged. Annealing at 500 °C and at higher temperatures caused a decomposition of the IQCs, and only the crystalline intermetallic phases Al6Mn and Be4AlMn could be found in the aAl matrix.
Keywords:quasicrystal, Al-Mn-Be alloy, thermal stability
Year of publishing:2012
Number of pages:str. 329-333
Numbering:št. 4, Letn. 46
ISSN:1580-2949
UDC:669.71'74'725:621.74.046
ISSN on article:1580-2949
COBISS_ID:16153366 New window
NUK URN:URN:SI:UM:DK:BN9GKLNX
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Downloads:95
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Record is a part of a journal

Title:Materiali in tehnologije
Shortened title:Mater. tehnol.
Publisher:Inštitut za kovinske materiale in tehnologije
ISSN:1580-2949
COBISS.SI-ID:106193664 New window

Document is financed by a project

Funder:EC - European Commission
Funding Programme:FP7
Project no.:226716
Name:European Light Sources Activities - Synchrotrons and Free Electron Lasers
Acronym:ELISA

Secondary language

Language:Slovenian
Title:Temperaturna obstojnost hitro strjenih trakov Al-Mn-Be
Abstract:Ikozaedrični kvazikristali (IQC) imajo kakor druge vrste fino razpršenih drobnih delcev utrjevalni učinek, ki ga lahko izkoristimo za povečanje trdnosti aluminijevih zlitin. V zlitinah Al-Mn-Be kvazikristali nastajajo že pri zmernih ohlajevalnih hitrostih, kakršne dosežemo pri postopkih litja, kot sta npr. kokilno litje in tlačno litje. Toda mikrostruktura, ki nastane pri teh postopkih litja, vsebuje tudi kristalne intermetalne faze in trdnostne lastnosti so slabše kot pri zlitinah z dvofazno mikrostrukturo (aAl-IQC). Dvofazno mikrostrukturo pa lahko dosežemo le z velikimi ohlajevalnimi hitrostmi, tj. s postopki hitrega strjevanja. Nadaljnja predelava hitro strjenih materialov pogosto poteka s postopki (kompaktiranje, iztiskovanje itd.), ki zahtevajo segrevanje. Pri tem materiala ne smemo pregreti, če želimo ohraniti utrjevalni učinek kvazikristalov. V okviru te raziskave so bili uliti hitro strjeni trakovi Al-Mn-Be s postopkom prostega litja na vrteče se kolo (angl.: melt spinning). Temperaturno obstojnost trakov hitro strjene zlitine smo ugotavljali z žarjenjem 24 h pri različnih temperaturah. Mikrostrukture trakov smo analizirali v litem stanju in po toplotni obdelavi z vrstičnim elektronskim mikroskopom z elektronskim in ionskim curkom (SEM-FIB), rentgensko difrakcijo (XRD) in z diferenčno dinamično kalorimetrijo (DSC). Trakovi so imeli v litem stanju dvofazno mikrostrukturo, sestavljeno iz matice aAl in fino dispergiranih kvazikristalov. Žarjenje pri temperaturah do 400 °C ni povzročilo razpada kvazikristalov in fazna sestava je ostala nespremenjena. Po žarjenju pri 500 °C ali višjih temperaturah pa je bila mikrostruktura sestavljena iz matice aAl in kristalnih intermetalnih faz Al6Mn ter Be4AlMn.
Keywords:kvazikristali, zlitina Al-Mn-Be, temperaturna obstojnost


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