复合熔盐净化剂优化对GH4169高温合金过冷的影响

摘要

采用复合熔盐净化法对GH4169高温合金的深过冷进行研究,通过正交实验优化出GH4169高温合金深过冷的最优净化剂及工艺参数,从而使GH4169高温合金获得了250K的大过冷度,同时探讨了复合熔盐净化剂及工艺参数作用机理;通过对不同过冷度下凝固组织的观察发现,随着过冷度的增加,合金组织明显细化,并发生两次晶粒转变,由树枝晶向粒状晶转变.当过冷度超过250K后,晶粒平均尺寸达到5.5μm.%The method of molten salt denucleating was applied to study the rapid solidification of GH4169 superalloy.The best compound molten salt and process parameters were gained through orthogonal experiment,then the maximum undercooling,250K,of GH4169 superalloy was achieved,at the same time,the mechanisms of molten salt and process parameters were also investigated; the solidification morphologies of the undercooled IN718 superalloy were found to be dependent on the degree of undercooling.Through observed the microstructures of GH4169 superalloy with variable undercooling,the solidification microstructure of IN718 underwent two grain refinement,which was transferred from dendrite structure to granular grain.When the undercooling achieved 250K,the average grain size was only 5.5μm.