Comments on the Paper “Production of Zr₅₅Cu₃₀Ni₅Al₁₀ Glassy Alloy Rod of 30 mm in Diameter by a Cap-Cast Technique” (Yoshihiko Yokoyama, Enrico Mund, Akihisa Inoue and Ludwig Schultz, Mater. Trans. 48 (2007) 3190–3192.)

Abstract

The authors of the title paper under discussion state the importance of low oxygen content in producing an amorphous top half in slowly cooled arc-melted buttons. Since the cooling rate does not favor the amorphous state in top half of the button, more evidence is needed to support the claim. Further, the authors made a liquid quenching machine to enhance the cooling speed to make larger ingots of the same alloy. It is not clear why a new machine with higher cooling rate is needed if the amorphous state can be achieved at lower cooling rates. Lack of essential details of the “cap-cast method” does not permit a critical assessment of the new process. The nature and quality of optical micrographs and HREM pictures are a cause of concern.