Ce-rich misch metal-based bulk metallic glasses with high glass-forming ability

Abstract

Ce-rich misch metal (Mm)-based bulk metallic glasses (Mm consists of Ce, La, Pr and Nd) with high glass-forming ability are developed in Mm-Co-Al alloy system. The critical diameter for glass-formation is 10, 5 and 3 mm, and the supercooled liquid region ΔTx, (ΔTx = T x-Tg, Tx is crystallization temperature and Tg is glass transition temperature) are 27, 90 and 79 K for Mm 65Co25Al10 (Mm65), Mm60Co 20Al20 (Mm60) and Mm55Co25Al 20 (Mm55) alloys, respectively. Reduced glass transition temperature Trg (Trg = Tg/Tm, where T m is melting temperature) is 0.62,0.65 and 0.69 for Mm65, Mm60 and Mm55, respectively. The employment of the misch metal, which comprises multi-rare earth elements, instead of pure Ce in the Ce-Al-Co system can improve the glass-forming ability in spite of the tiny atomic size difference of the rare earth metals. The present alloy system is an exception to the criteria of ΔTx, Tg/Tm and different atomic size distribution as well as negative heat of mixing used for evaluating the relative GFA. © 2005 The Japan Institute of Metals.