镍基单晶高温合金DD2梯度定向凝固行为  

SOLIDIFICATION BEHAVIOUR OF Ni-BASE SINGLE-CRYSTAL SUPERALLOY DD2

作　　者：杜炜[1] 魏朋义[2] 李建国[2] 傅恒志[2] 孙家华[3] 

机构地区：[1]西北工业大学凝固技术国家重点实验室,西安710072 [2]西北工业大学 [3]钢铁研究总院

出　　处：《航空材料学报》1997年第2期1-5,共5页Journal of Aeronautical Materials

摘　　要：利用高梯度（250K／cm）走向凝固装置（LMC），对不同凝固条件下DD2单晶高温合金的定向凝固行为进行了研究。结果表明，在一定温度梯度下，通过改变凝固速率可以得到以平面状、胞状、树枝状凝固界面生长的DD2单晶；随着冷却速率的增大，一次枝晶间距减小、组织均化，且所得一次枝晶间距与凝固参数的关系基本符合Hunt模型。With the help of high-temperature-gradient directional solidification equipment (LMC), the solidifica-tion behavior under high temperature gradient of DD2 single crystal superalloy was investigated. The mor-phology of liquid/solid interface during solidification, primary dendrite arm spacing and side-branch coars-ening kinetics, and microstructure were examined in specimens obtained under different growth rate. Theresults show that, when the temperature gradient keeps constant, with the increase of the growth rate,single crystal specimens of DD2 reveal the planar, cellular and dendrite interface structure in sequence-The primary dendrite arm spacing decreases with the increase of cooling rate. The amount of γ/γ’ eutecticin fine dendrite is larger but smaller in size than that in the coarse dendrite. When the cooling rate is much higher, superfine columnar dendrite are formed, and the amount of γ/γ’ eutectic decreased.

关 键 词：单晶 高温合金 定向凝固 枝晶间距 温度梯度 

分 类 号：TG132.32[一般工业技术—材料科学与工程] TG111.4[金属学及工艺—合金]