Rapid solidification of undercooled eutectic and monotectic alloys
Rapid solidification of undercooled eutectic and monotectic alloys
复制标题
DOI：
10.1016/0921-5093(93)90244-9
复制
发表时间：
1993-12
期刊：
影响因子：
6.4
通讯作者：
B. Wei;D. Herlach;F. Sommer;W. Kurz
中科院分区：
文献类型：
--
作者：
B. Wei;D. Herlach;F. Sommer;W. Kurz
Co-34.2wt.%Sn 共晶合金和 Ni-5wt.%Ag 偏晶合金的大块样品过冷度分别高达 244 K 和 313 K。测量重辉速度作为过冷度的函数，并确定实际晶体生长速度的上限。理论计算也是在现有的共晶和枝晶生长理论的基础上完成的。当过冷度超过 57 K 时，观察到“层状共晶-异常共晶”微观结构转变，这与 Trivedi-Magnin-Kurz 的预测一致，即规则层状共晶存在最大生长速度。在高度过冷的偏晶合金熔体中，液态银相似乎优先形核。 α-Ni 相呈树枝状生长，并通过银滴的聚结促进样品底部和顶部宏观偏析的形成。
Bulk samples of Co-34.2wt.%Sn eutectic alloy and Ni-5wt.%Ag monotectic alloy were undercooled by up to 244 and 313 K respectively. The recalescence velocities were measured as a function of undercooling, and determine the upper limits of the actual crystal growth velocities. Theoretical calculations were also accomplished on the basis of the current eutectic and dendritic growth theories. A “lamellar eutectic-anomalous eutectic” microstructural transition was observed for undercoolings of more than 57 K, which agrees qualitatively with Trivedi-Magnin-Kurz's prediction that there is a maximum growth velocity for regular lamellar eutectic. In the highly undercooled monotectic alloy melt, liquid Ag phase seemed to nucleate preferentially. The α-Ni phase grew dendritically and facilitated the formation of macrosegregation at the bottom and top of the sample through coalescence of Ag droplets.