A fundamental studies on wetting between molten metal and a chill block and crystal growth from the chill block

使用碳钢、Al-Cu二元合金、Al-Si共晶合金和Sn-Sb二元合金，通过浸渍技术形成薄壳。对型壳的形状和型壳冷侧面的表面进行了研究。从实验结果得到以下结果：(1)在型壳的冷侧面表面形成了类似龟甲的图案，并且对应于型壳的凹入区域，其中凝固被延迟。 (2)在亚包晶碳钢中形成不平坦的壳。 (3)低碳钢中形成激冷区，高碳钢中形成细小的枝晶。延伸的枝晶由冷晶和细枝晶生长。在亚包晶碳钢中，由于激冷晶体和细枝晶的混合，粗大的枝晶随机生长，因此凝固过程不均匀。 (4)Al-Cu二元合金和Al-Si合金在型壳冷硬面表面形成波纹痕，但这并不是由型壳生长不均匀造成的。 (5)在Sn-Sb二元合金中，在型壳冷硬侧表面观察到纽扣痕迹，其对应于Sn-Sb型壳的凸出区域。 (6)Al-Cu壳层的垂直和水平方向周期性地发生不均匀生长，但Al-Si壳层仅在水平方向发生不均匀生长。 (7)计算机模拟中应引入耐热性，以引起凝固壳的不均匀生长。从上述结果来看，凝固壳的形成有两种类型。一是它直接取决于成核，例如 Sn-Sb 合金。另一个是它取决于形核、潜热和热应力引起的固体变形之间的相关性。

Using carbon steels, Al-Cu binary alloys, an Al-Si eutectic alloy, and a Sn-Sb binary alloy, a thin shell was formed by a dipping technique. The shape of the shell and the surface in the chill side of the shell were investigated.Following results were obtained from experimental results.(1) The pattern like a tortoise shell was formed in the surface of the chill side of the shell and corresponds to the concave region of the shell, in which solidification retarded. (2) An uneven shell was formed in a hypoperitectic carbon steel. (3) A chill zone was formed in the steel containing low carbon content and fine dendrites were formed in the steel containing high carbon content. Extended dendrites grew from the chill crystals and the fine dendrites. In a hypoperitectic carbon steel, the extended dendrites grew randomly based on the mixing of the chill crystals and the fine dendrites, so that solidification proceeded unevenly. (4) Ripple marks was formed in the surface of the chill side of the shell in Al-Cu binary alloys and an Al-Si alloy, but it weren't depend on the uneven growth of the shell. (5) Button marks were observed in the surface of the chill side of the shell in a Sn-Sb binary alloy and it corresponded to the convex region of the Sn-Sb shell. (6) An uneven growth occurred periodically in vertical and horizontal directions of the Al-Cu shell, but it was occurred only a horizontal direction of the Al-Si shell. (7) Heat resistance should be introduced to computer simulation in order to cause the uneven growth of the solidifying shell.Considering from above results, there are two types of the shell fromation. One is that it depends directly on nucleation such as a Sn-Sb alloy. The other is that it depends on the correlation among nucleation, latent heat and solid deformation due to thermal stress.