镍基单晶高温合金中γ′相的类树枝晶生长特征  

PSEUDO-DENDRITE GROWTH CHARACTERISTICS OF γ′PRECIPITATES IN SINGLE CRYSTAL NICKEL BASE SUPERALLOY

作　　者：张静华[1] 姚向东[1] 张志亚[1] 李英敖[1] 管恒荣[1] 胡壮麒[1] 

机构地区：[1]中国科学院金属研究所

出　　处：《金属学报》1994年第10期A453-A462,共10页Acta Metallurgica Sinica

摘　　要：镍基单晶高温合金经充分均匀化、高温固溶和直接按时效处理后，沉淀出一种类树枝晶形态γ′相．类树枝晶γ′相的析出温度（Ｔ_（ｓγ′））敏感于局部合金成分，它的形核密度（Ｉ）与过冷度（△Ｔ_（γ′））成指数关系：Ｉ（μｍ^（－２））＝２．５×１０^（－３）ｅｘｐ（０，１１△Ｔ_（γ′））．在较小过冷度，类树枝晶γ′相尺寸与直接时效时间成正比．它的择优生长方向是〈１１０〉，与基体取向相同，完全共格．类树枝晶γ′的形核机制包括扩散和非扩散两种，并趋向对称形核．An investigation has been made of the nucleation and growth characteristics of the pseudo-dendritic γ′precipitates in a single crystal nickel base superalloy which is directly aged after homogenizing and solutioning at high temperature. The results show that the temperature for the pseudo-dendritic γ′ precipitation is sensitive to the alloy composition in local area and that the relationship between the nucleation density (Ⅰ) and undercooling (△Tγ′) for the pseudo-dendritic γ′ precipitates is given by logarithmic expression: I(μm￣2) = 2.5×10￣(-3) exp(0. 11△T_(γ′)). The size of the pseudo-dendritic γ′precipitates is proportional to the direct aging time under small undercooling. The preferential growth direction of the pseudo-dendrite γ′precipiatates is <110> which is completely coherent with matrix. The formation mechanism for pseudo-dendrite γ′prencipitates involves both the diffusion and non- diffusion controlled. It intends to form nucleus symmetrically

关 键 词：类树枝晶相 单晶高温合金 时效 

分 类 号：TG132.32[一般工业技术—材料科学与工程]