采用大体积液态金属的微观净化技术，在Ni—Ni3Si合金系中使Ni-（6．07—19．7）％Si和Ni-（20.5—22）％Si两组合金分别获得了最大达344和265K的极限形核过冷度，并使其极限过冷度保持20个循环过热周期不衰减.实验发现，Ni—Ni3Si系近共晶合金深过冷凝固时，Ni3Si总是领先于α（Ni）相形核.根据实验数据和表面异质形核速率模型，求得Ni3Si和α（Ni）相异质形核时的异质形校因子f（θ）分别为0．069和0.28;求得过冷熔体中Ni3Si和α（Ni）相等形核速率时的温度-成分曲线完全处于共晶点左侧，表明在近共晶成分过冷熔体中，小平面相Ni3Si易于α（Ni）形核 The micro-purifying technology of large volume liquid metal was used to make the Ni-(6.07-19.7)% Si and Ni- (20.5-22)% Si two groups of alloys up to 344 And the critical nucleation supercooling degree of 265K, and the ultimate supercooling degree is maintained for 20 cycles without overheating.The experimental results show that Ni3Si is always ahead of α Ni) nucleation.According to the experimental data and the surface heterogeneous nucleation rate model, the heterogeneous causality factor f (θ) of Ni3Si and α (Ni) phase heterogeneous nuclei were found to be 0.069 and 0.28, respectively. The temperature-composition curves at the same nucleation rate of Ni3Si and α (Ni) in the cold melt are completely on the left side of the eutectic point, indicating that Ni3Si in the near-eutectic composition is prone to α (Ni) nucleation