2022 Volume 36 Issue 2 Pages 220-228
The rapid cooling single-roll method is widely used to produce amorphous metal ribbons. To obtain more rapid and homogeneous cooling in the method, one needs to prevent the molten metal / solid interface from forming gas pores. We experimentally investigated the pore formation mechanism by directly observing the impact dynamics with the solidification of molten tin drops on a glass and sapphire substrate under an argon gas environment. We also measured the time variation in the temperature distribution on the substrate surface. As a result, we clarified that pores were formed mainly on the poorly conductive substrate, glass. In contrast, on the highly conductive substrate, sapphire, intermittent solidification layers were formed with thin gas layers between them. Furthermore, we derived two characteristic time scales for solidification relating to the sensible and the latent heats by employing one-dimensional thermal conduction analysis.
