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对熔融玻璃净化后深过冷Ni-21.4%Si(原子分数,下同)共晶合金的凝固特性进行了实验研究,并对其均质形核过冷度进行了理论预测.结果发现,采用熔融玻璃净化可使Ni-21.4%Si共晶合金获得318 K的过冷度.理论计算表明,此过冷度达到了Ni-21.4%Si共晶合金的均质形核过冷度.Ni-21.4%Si共晶合金凝固特性与过冷度△T有关:当过冷度小于250 K时,冷却曲线有2个再辉峰,其中当过冷度小于206 K时,凝固组织由Ni3Si相和规则共晶组成,当过冷度在206 K到250 K之间时,凝固组织由α-Ni相和规则共晶组成;过冷度大于250 K后,冷却曲线只有1个再辉峰,凝固组织为反常共晶.过冷度会影响初生相Ni3Si的生长方式.随着过冷度的增大,初生相Ni_3Si的生长会由小平面生长方式转为非小平面生长方式.
The solidification behavior of deep undercooled Ni-21.4% Si (atomic fraction) eutectic alloy after the purification of molten glass was studied, and the theoretical predictions of its homogeneous nucleation undercooling were carried out. The results show that, The purification of molten glass can make the undercooling of Ni-21.4% Si eutectic alloy to 318 K. The theoretical calculation shows that this undercooling achieves homogeneous nucleation undercooling of Ni-21.4% Si eutectic alloy.Ni- The solidification behavior of 21.4% Si eutectic alloy is related to the undercooling △ T: when the undercooling is less than 250 K, the cooling curve has two re-bright peaks. When the undercooling is less than 206 K, the solidification structure consists of Ni3Si phase and Regular eutectic composition, when the undercooling is between 206 K and 250 K, the solidified microstructure consists of α-Ni phase and regular eutectic. When the undercooling degree is over 250 K, the cooling curve has only one re-hugh peak, The organization is abnormal eutectic.The undercooling will affect the growth of primary phase Ni3Si.With the increase of undercooling, the growth of primary phase Ni_3Si will change from facet growth to non-facet growth.