深过冷Ni-Cu-Si合金熔体中的快速枝晶生长

为了揭示多元合金中的枝晶生长规律,采用电磁悬浮技术实现了Ni-10%Cu-10%Si三元合金的深过冷与快速凝固,实验中合金熔体获得的最大过冷度为236K。对合金快速凝固过程中初生相-αNi的枝晶生长速度测定结果表明,其与过冷度之间存在幂函数关系:V=1.6×10-13ΔT5.7。当ΔT较小时,随着ΔT的增加V增加缓慢,当ΔT较大时,随着ΔT的增加V迅速增加。对比分析表明,溶质Si对-αNi枝晶的生长影响显著,而溶质Cu则几乎没有影响。随着过冷度的增加,未发现-αNi相的微观形态从枝晶向等轴晶转变,但-αNi晶粒尺寸均随着过冷度的增加而急剧细化。

Rapid Dendritic Growth in a Deep Undercooled Melt of Ni-Cu-Si Alloy

For discovering the dendrite growth mechanism in multicomponent alloys,deep undercooling and subsequent rapid solidification of Ni-10%Cu-10%Si ternary alloy are achieved by employing the electromagnetic levitation processing technique.The maximum undercooling of 236K is obtained in experiments.The dendrite growth velocity of α-Ni,the primary phase,is measured,and the results indicate that the velocity depends on undercooling with a power function relationship as V=1.6×10^-13ΔT^5.7.A comparative analyse shows that the solute of Si has significant influence on the dendrite growth of α-Ni during rapid solidification,conversely the influence of the solute of Cu is negligible.With the undercooling increasing,no transition of the microstructure of α-Ni from dendrite to equiaxed grains occurs,but the grains of α-Ni refined abruptly.