Glass forming ability and crystallisation processes within the Al±Ni±Sm system M. Gich a , T. Gloriant a,1 ,S.Suri ~ nach a , A.L. Greer b ,M.D.Bar o a, * a Departament de F  õsica, Facultat de Ci  encies, Universitat Aut  onoma de Barcelona, F  õsica de Materials 2, Edi®ci Cc, 08193 Bellaterra Barcelona), Spain b Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, UK Received 1 August 2000 Abstract Several melt-spun ribbons of dierent compositions in the Al-rich corner of the Al±Ni±Sm ternary system were analysedbymeansofX-raydiractionXRD)anddierentialscanningcalorimetryDSC)inordertodeterminetheir thermal stability and to understand the nanocrystallisation process. Out of all the compositions analysed, only three werefoundtobecompletelyamorphous,whereastheotherswerepartiallycrystallised.Theactivationenergiesofthe a- Al nanocrystallisation were evaluated using the Kissinger method. Isothermal DSC scans revealed the existence of quenched-in nuclei in the more unstable amorphous alloys. These quenched-in nuclei are probably due to the melt- spinning process and the crystalline structure after devitri®cation is strongly dependent on them. Ó 2001 Elsevier Science B.V. All rights reserved. PACS: 61.43.Dq; 61.46.+w; 61.82.Rx; 68.60.Dv 1. Introduction The new family of Al-based amorphous alloys discovered in 1987) with a combination of a late transition metal LTM) and rare earth RE) sol- utesobtainedbyrapidliquidquenching[1,2]isan importantresearch®eldbecauseoftheremarkable mechanical properties useful for industrial appli- cations[3].Theas-quenchedamorphousstructures are ductile and exhibit high value of tensile strength[4,5],hardness[6],andmorerecentlywear [7] and corrosion resistance [8]. These properties canbefurtherincreasedaftertheprecipitationofa thermally induced homogeneous dispersion of a- Alnanoparticles[9].Nevertheless,thelowthermal stability of these materials still limits their tech- nological applications, and what is needed are al- loys with improved thermal stability so that they can withstand the compacting processes required for obtaining massive products. Both for opti- mising the thermal stability and mechanical properties, an understanding of the intimately re- lated factors governing glass formation and devi- tri®cation processes is desirable. Among the Al±LTM±RE systems, the Al±Ni± RE alloys [10] have been intensively studied, par- ticularly for RE  Y, La, Ce, and Nd [11], due to Journal of Non-Crystalline Solids 289 2001) 214±220 www.elsevier.com/locate/jnoncrysol * Corresponding author. Tel.: +34-93 581 1657; fax: +34-93 581 2155. E-mail address: dolors.baro@uab.es M.D. Bar o). 1 Present address: INSA, Laboratoire de M etallurgie, G.R.C.M. EA 2620), 35043 Rennes c edex, France. 0022-3093/01/$ - see front matter Ó 2001 Elsevier Science B.V. All rights reserved. PII:S0022-309301)00650-0