单晶DD3合金在混合盐介质中的蠕变和断裂特性

应用扫描电镜、剖面分析和ＥＤＡＸ能谱分析，研究了单晶ＤＤ３合金及其带Ｐｔ－Ａｌ涂层试样在空气和混合盐两种不同介质中的高温蠕变及断裂行为。试验表明：在空气环境中，涂层对蠕变性能影响不大；在混合盐介质中，涂层能有效地提高ＤＤ３合金的蠕变寿命和蠕变延伸率，防止合金在热腐蚀环境中的早期失效。本文还提出一个新的断裂模型，以解释ＤＤ３合金高温蠕变时的断裂行为

CREEP AND FRACTURE FEATURE OF DD3 SINGLE CRYSTAL NICKEL-BASE SUPERALLOY IN MIXED SALT ENVIRONMENT

An investigation was made on the high temperature creep and fracture behaviour tested in air and in mixed salt(10% NaCl 90%Na2SO4) environment for both single crystal Ni-base superalloy DD3 without or with Pt-Al coatings. The results show that in mixed salt, Pt-Al coating can improve creep-rupture life, however, in air, no effect on the creep-rupture properties of DD3 at elevated temperature: the creep strength of DD3 would drop suddenly in hot corrosion environment; and owing to the interaction betwween creep and hot corrosion, the formation of corrosion products leads to premature failure of the superalloy. A new fracture model is proposed to explain the creep fracture behaviour of superalloy DD3 at elevated temperatures.