冷却速率对Ni-Nb合金非平衡凝固组织的影响

发布时间：2018-05-01 18:49

本文选题：Ni-Nb合金 + 冷却速率　；参考：《稀有金属材料与工程》2015年06期

【摘要】：采用阶梯铜模喷铸方式开展了Ni-10%Nb(质量分数)合金非平衡凝固实验,并利用Procast软件对不同铜模内径所对应的冷却速率进行了计算。综合采用光学显微镜、扫描电镜及能谱分析仪对不同冷速条件下合金二次枝晶间距、溶质含量等组织参量进行表征。实验结果表明,随铜模内径减小,合金冷却速率增加,二次枝晶间距减小,枝晶主干中溶质含量得到明显提高。在此基础上,利用枝晶生长模型对不同过冷度条件下的枝晶生长速率进行了计算。分析结果表明,随冷却速率增加,凝固发生时过冷度增大,枝晶生长速度提高,溶质截留现象趋于严重,导致溶质过饱和现象发生。此外,冷却速率的提高还有利于减小液/固界面前沿溶质扩散区长度,导致二次枝晶间距减小。
[Abstract]:The non-equilibrium solidification experiments of Ni-10 NB (mass fraction) alloy were carried out by means of step copper mold spray casting, and the cooling rates corresponding to different internal diameters of copper dies were calculated by Procast software. The secondary dendrite spacing and solute content of the alloy were characterized by optical microscope, scanning electron microscope and energy dispersive spectrum analyzer. The experimental results show that the cooling rate increases, the secondary dendrite spacing decreases, and the solute content in the dendrite trunk increases with the decrease of copper die diameter. On this basis, the dendritic growth rate under different undercooling conditions was calculated by using dendritic growth model. The results show that with the increase of cooling rate, the undercooling degree increases, the dendritic growth rate increases, and the solute retention becomes more serious, which leads to the phenomenon of solute supersaturation. In addition, the increase of cooling rate can also reduce the length of solute diffusion zone at the front of the liquid-solid interface, resulting in the decrease of secondary dendritic spacing.
【作者单位】：南昌航空大学轻合金加工科学与技术国防重点学科实验室;中航工业南方航空工业集团有限公司;
【基金】：国家自然科学基金(51164028) 江西省教育厅青年基金(GJJ12446) 轻合金加工科学与技术国防重点学科实验室开放课题GF201201003)
【分类号】：TG292

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