Yttrium-carbon phase diagram

Here, the so-called heavy lanthanides include the elements from samarium to-lutetium, except for ytterbium and europium which behave like bivalent metals and have unique properties. For these heavy-lanthanide-carbon systems, no complete phase diagram was found, only some information about the formation and the crystal structure of the carbides is available. On the basis of these data the general characteristics of the phase diagrams of the heavy-rare-earth-carbon systems can be summarized. In this case the yttrium-carbon phase diagram may be regarded as the best prototype available for compounds of the heavy lanthanide systems with carbon. 

Summarizing the phase relationship in the heavy-lanthanide-carbon systems and the general characteristics with respect to formation of the carbides, it can be concluded that the phase diagram of the yttrium-carbon system is a good prototype of the heavy-lanthanide-carbon systems, which have not yet been studied in detail. In addition, on the basis of the yttrium-carbon phase diagram the unknown information about the R C phase diagrams could be deduced. 

Phase diagram of the yttrium-carbon system The phase diagram of the yttrium-carbon system was proposed by Carlson and Paulson (1968) and refined by Storms (1971), is shown in fig. 2. 

Nasonov and co-workers have investigated the phase equilibria of the aluminium-rare-earth-metal-carbon systems and given partial phase diagrams for the aluminium-(scandium, yttrium, lanthanum, gadolinium and erbium)-carbon systems (Nasonov 1981, Nasonov et al. 1988) in the Al-rich region at 572°C. However, we were unable to obtain their reports because of lack of international academic exchanges. 

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