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本文研究高温固溶处理对一种定向凝固高强度镍基高温合金的组织和性能的影响。实验结果表明,细小γ′尺寸(α)和体积分数(ν_f)都随固溶温度的升高而增大。随着固溶温度的升高,持久寿命延长,而第二阶段蠕变速率降低。经1210—1250℃高温固溶并900℃,16h时效处理(空冷)后,合金可成倍延长760℃,66kgf/mm~2的持久寿命(τ_f),而第二阶段蠕变速率((?))却随之降低,它们之间的关系符合(?)~(m·τ_f=c,其中m≈1,c=8.0.第二阶段蠕变速率((?))是细小γ′尺寸(α)和体积分数(ν_f)综合作用的结果,且εαα/ν_f~(2/3)。用透射电镜观察了第二阶段蠕变过程位错亚结构的变化。在中温第二阶段蠕变下,在γ基体上存在高密度的不规则的三维位错网络,而在γ′粒子中,只发现少数位错对;在高温第二阶段蠕变下,在γ/γ′界面上形成规则的二维位错网络。按照位错攀移模型,提出一种第二阶段蠕变机理。
This article studies the effect of high temperature solution treatment on microstructure and properties of a directional solidified high strength Ni-based superalloy. The experimental results show that the fine γ ’size (α) and the volume fraction (ν_f) both increase with increasing solution temperature. As the solution temperature increases, the life expectancy increases, while the creep rate decreases in the second stage. After the solid solution at 1210-1250 ℃ and aging treatment at 900 ℃ for 16h (air cooling), the alloy can extend the life expectancy (τ_f) at 760 ℃ and 66kgf / mm ~ 2 exponentially, while the creep rate in the second stage (? )), The relationship between them is in accordance with (?) ~ (M · τ_f = c, where m≈1, c = 8.0) The creep rate in the second stage α) and volume fraction (ν_f), and εαα / ν_f ~ (2/3). The changes of dislocation substructure in the second stage of creep process were observed by transmission electron microscopy. , There is a high density of irregular three-dimensional dislocation networks on the γ matrix, whereas only a few dislocation pairs are found in the γ ’particles; at the γ / γ’ interface, a regular Two-dimensional dislocation network. According to the dislocation climbing model, a second-stage creep mechanism is proposed.