硼含量对镍基合金GH4049晶界析出相和高温性能的影响

在晶界面上用萃取碳复型技术研究了镍基合金GH4049(Ni-15Co-10Cr-5．5W-5Mo-4．2Al-1．5Ti)中与B和C的晶界偏聚效应密切相关的二次析出相特征．B含量低于0．008％时，因固溶B／C(原子比)很低，晶界析出大尺寸MC薄膜和M6C枝晶片以及薄膜状M23C6，不利于高温塑性和持久寿命．B含量为0．011％和0．018％时，固溶B／C(原子比)虽仅为0．667和0．941，已可减少和全部抑制上述碳化物的析出，代之以弥散M3B2颗粒，高温性能大幅度上升．但B含量过高，M3B2密集析出，高温性能下降．降低固溶冷却速度而使B和C原子向晶界长程偏聚，可促进M3B2析出，改善MC的形貌并抑制M6C和M23C6析出。

Effects of Boron Content on Boundaries Precipitates in Ni Base Alloy GH4049 and Its High Temperature Properties

Characteristics of the secondary precipitates on grain surfaces connected with segregation of boron and carbon elements in a Ni-15Co-10Cr-5.5W-5Mo-4.2Al-1.5Ti alloy (GH4049) were studied by using extraction carbon replica method. When B content was below 0.008%,or the solid-solutioned B/C atom ratio was decreased to about 0.365, the high temperature ductility and stress rupture life were reduced because large MC films, dendritic flake M6C and fine M23C6 films precipitated at grain boundaries. When B contents were 0.011% and 0.018%, or the solid-solutioned B/C atom ratios were 0.667 and 0.941, the amounts of these carbides were decreased or their precipitates were refrained, but particles M3B2 precipitated, which improves the high temperature properties markedly. When B content was excessively high, M3B2 particles precipitated densely, resulting in the decrease of high temperature properties. If decreasing the cooling rate after solution, B and C atoms can diffuse at long distance, which promotes the precipitate of M3B2 particles at grain boundaries, improves the morphology of MC, and depresses the precipitations of M6C and M23C6.