抄録
The meta-stable phase formed from the undercooled melt was reviewed in metallic and oxide materials. Three differ- ent conditions have to be satisfied for the meta-stable phase to be formed from the undercooled melt. The first one is deep undercooling below the hypothetical melting temperature of the meta-stable phase. The second one is the solid-liquid interface energy of the meta-stable phase to be less than that of the stable phase. The last one is that the growth velocity of the meta-stable phase is larger than that of the stable phase. In Fe-based alloys without the y loop such as Fe76 ix o 4 x, the meta-stable b phase can be formed when the melt of hyper-eutectic composition is undercooled below the critical temperature where the energy barrier for the critical nucleus of the b phase to be formed is less than that of the y phase. In rare-earth ferrites such as YFe0 , the meta-stable phase can be formed provided that the same conditions as those in the metallic materials are satisfied.
