E䨻S Joural of the European Ceramic Society2) Progress in SiAlON ceramics V.A.Izhevskiya.L.A.Genovaa J.C.Bressiania F.Aldinger b.* Abstract d on heating.Regular Keywords:Phase equilibria:Phase transformations:SiAlONs;Sintering Contents 1.Introduction. 2276 2.nitrogen melilite and nitrogen wochlerite solid solutions .2277 3.Subsolidus phase relationships in R2O-SiaN-AIN-Al2O;systems. 2282 4.Thermal stability of RE--SiAIONs and the reversibility ofto B'transformation. 2285 5.Reaction densification ofa and (+B)SiAlONs. 2290 2293 Acknowledgement 2293 References .2293 *Corres E-mnait c Ukraine.Kiev Progress in SiAlON ceramics V.A. Izhevskiy a,1, L.A. Genova a , J.C. Bressiani a , F. Aldinger b,* a Instituto de Pesquisas EnergeÂticas e Nucleares, IPEN/CNEN-SP, Trav. R, 400, Cidade UniversitaÂria, SaÄo Paulo, SP-05508-900, Brazil bMax-Planck-Institut fuÈr Metallforschung und UniversitaÈt Stuttgart, Institut fuÈr Nichtmetallische Anorganische Materialien, Heisenbergstrasse 5, D-70569, Stuttgart, Germany Received 9 June 1999; received in revised form 21 December 1999; accepted 30 January 2000 Abstract In view of the considerable progress that has been made over the last several years on the fundamental understanding of phase relationships, microstructural design, and tailoring of properties for speci®c applications of rare-earth doped SiAlONs, a clear review of current understanding of the basic regularities lying behind the processes that take place during sintering of SiAlONs is timely. Alternative secondary phase development, mechanism and full reversibility of the a0 to b0 transformation in relation with the phase assemblage evolution are elucidated. Reaction sintering of multicomponent SiAlONs is considered with regard of wetting behavior of silicate liquid phases formed on heating. Regularities of SiAlON's behavior and stability are tentatively explained in terms of RE element ionic radii and acid/base reaction principle. # 2000 Elsevier Science Ltd. All rights reserved. Keywords: Phase equilibria; Phase transformations; SiAlONs; Sintering 0955-2219/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved. PII: S0955-2219(00)00039-X Journal of the European Ceramic Society 20 (2000) 2275±2295 Contents 1. Introduction......................................................................................................................................................... 2276 2. Occurrence of nitrogen melilite and nitrogen woehlerite solid solutions containing aluminum ........................... 2277 3. Subsolidus phase relationships in R2O3±Si3N4±AlN±Al2O3 systems ................................................................... 2282 4. Thermal stability of RE-a-SiAlONs and the reversibility of a0 to b0 transformation.......................................... 2285 5. Reaction densi®cation of a and (a+b) SiAlONs ................................................................................................2290 6. Conclusions..........................................................................................................................................................2293 Acknowledgements................................................................................................................................................... 2293 References ................................................................................................................................................................ 2293 * Corresponding author. E-mail address: aldinger@aldix.mpi- stuttgart.mpg.de (F. Aldinger). 1 Invited scientist, on leave from the Institute for Problems of Material Science, National Academy of Sciences of Ukraine, Kiev, Ukraine