近等原子比NiTi合金中微观缺陷和电子密度的正电子湮没研究  

Microdefects and Electron Densities in Near-Equiatomic NiTi Alloys Studied by Positron Annihilation Spectroscopy

作　　者：胡益丰[1] 邓文[2] 

机构地区：[1]江苏理工学院,江苏常州213001 [2]广西大学,广西南宁530004

出　　处：《稀有金属材料与工程》2013年第8期1581-1584,共4页Rare Metal Materials and Engineering

基　　金：the Scientific Research Fund Project of Jiangsu University of Technology(KYY12020);the National Natural Science Foundations of China(50361002);the Foundations of Natural Science of Guangxi(0448006)

摘　　要：用正电子寿命谱测量方法研究了5种不同化学成分的近等原子比NiTi合金中的微观缺陷和自由电子密度。结果表明,当Ni原子和Ti原子形成NiTi合金时部分3d电子被局域化而形成共价键,导致合金中参与形成金属键的自由电子减少。近等原子比的NiTi合金中的基体和缺陷处的自由电子浓度均随Ni含量的增加而改变,并且当Ni含量为51 at%时达到最大值。研究还发现Ni51Ti49合金含有最少的缺陷,从而有助于马氏体相变的发生,这可能成为Ni51Ti49合金具有最好的形状记忆效应的一个原因。Microdefects and free electron densities in near-equiatomic NiTi alloys of five different chemical compositions have been studied by positron lifetime measurements. The results indicate that some 3d electrons are localized to form covalent bonds when Ni and Ti atoms aggregate to form NiTi alloys, leading to the decrease of the free electrons participating in metallic bonds. The densi- ties of free electrons in the bulk and defects of near-equiatomic NiTi alloys change with the increase of Ni content and reach the maximum value with 5 1.0% Ni （atom fraction）. It is also found that the Ni51Ti49 alloys have the fewest defects, which contributes to the Martensite transformation. Consequently, the Ni51Ti49 alloys have the best shape memory effect.

关 键 词：NITI合金 微观缺陷 电子密度 形状记忆效应 

分 类 号：TG111[金属学及工艺—物理冶金]