NiTi形状记忆合金中异常的多步马氏体相变研究  

Research on Novel Multi-step Martensitic Transformation in NiTi Shape Memory Alloys

作　　者：袁斌[1] 梁锦霞[1] 李浩[1] 曾美琴[1] 

机构地区：[1]华南理工大学机械工程学院,广州510641

出　　处：《材料导报》2007年第11期60-63,79,共5页Materials Reports

基　　金：中国博士后科学基金(20060390199);华南理工大学自然科学基金

摘　　要：马氏体相变是NiTi记忆合金具有优良形状记忆效应和超弹性的本质原因。通常,NiTi合金是以一步(B2-B19′)或者两步(B2-R-B19′)来完成马氏体相变。但在某些条件下,NiTi合金会展现出异常的多步马氏体相变行为。综述了NiTi合金中各种类型的多步马氏体相变行为,并给出了它们出现的条件以及形成的机理。富镍的NiTi记忆合金在中温(400～500℃)时效时会出现三步马氏体相(B2-R-B19′和B2-B19′组成),这是由于Ni_4Ti_3相在晶界处优先析出所造成的。而在低温(200～300℃)时效时,出现的两步B2-R和一步R-B19′的异常马氏体相变则是由于B2相基体中晶界和晶内的成分不均匀,而这种不均匀性又是由于Ni_4Ti_3相在晶界处的优先析出所导致的。The martensitic transformation is the intrinsical cause of NiTi shape memory alloy （SMA） with excellent shape memory effect （SME） and superelasticity. In general, NiTi SMA exhibits one step （B2-B19′） or two step （B2-R-B19′） martensitic transformation behavior. However, NiTi SMA would show some novel multi-step martensitic transformation behaviors under certain condition. This paper reviews all types of multi-step martensitic transformation behaviors, and their forming conditions and mechanisms. An abnormal three-step martensitic transformation behavior （B2-R-B19′ and B2-B19′） is found in Ni-rich Ti-Ni alloys when aged at intermediate temperatures （400～500℃）. This strange behavior is due to preferential precipitation of Ni4 Ti3 phase at grain boundary. However, it is found that R-phase transformation occurs in two steps, when aged at low temperatures （200-300℃）. The abnormal two-step R-phase transformation is attributed to a large-scale heterovneity of Ni-content between grain boundary region and grain interior, which results from the preferential precipitation in grain boundary regions.

关 键 词：NITI形状记忆合金 马氏体相变 Ni4Ti3相 

分 类 号：TG139.6[一般工业技术—材料科学与工程]