NiTi形状记忆合金中缺陷和电子密度的正电子湮没研究  

Microdefects and Electron Densities in NiTi Shape Memory Alloys Studied by Positron Annihilation

作　　者：胡益丰[1] 沈大华[1] 邓文[2] 

机构地区：[1]江苏技术师范学院,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》2009年第1期38-41,共4页Rare Metal Materials and Engineering

基　　金：江苏省普通高校自然科学研究计划资助项目(07KJD430041);江苏技术师范学院青年科研基金项目(KYY06094);国家自然科学基金项目(50361002)资助

摘　　要：用正电子寿命谱测量法研究了Ni50.78Ti49.22合金B2相、R相和B19’相的微观缺陷和自由电子密度。通过比较Ni50.78Ti49.22合金在285和227K时的寿命谱参数,可以发现R相的自由电子密度比B2相的低;R相缺陷的开空间较大,但其缺陷浓度比B2相的低。在100K时Ni50.78Ti49.22合金处于B19’相。与R相相比,B19’相的自由电子密度增加,缺陷的开空间减小,同时缺陷浓度增大。随着温度的降低,Ni50.78Ti49.22合金中的微观缺陷和自由电子在多阶段马氏体转变中(B2→R→B19’相转变)起着重要作用。The microdefects and free electron densities in B2, R and B19＇ phases of Nis0.78Ti49.22 alloy have been studied by positron lifetime measurements. Comparing the lifetime parameters of the Ni50.78Ti49.22 alloy measured at 285 and 227 If, it is found that the free electron density of the R phase is lower than that of the B2 phase; the open volume of the defects for the R phase is larger, while the concentration of these defects is lower than that of the B2 phase. The Ni50.78Ti49.22 alloy is the B19＇ phase at 100 K. In comparison with the R phase, the free electron density of the B19＇ phase increases, the open volume of defects for the B19＇ phase decreases, and the concentration of these defects increases. It is found that the microdefects and the free electron density play important roles during the multi-step transformations （B2→R→B 19＇） for the Ni50.78Ti49.22 alloy with the temperature decreasing.

关 键 词：NITI合金 微观缺陷 电子密度 马氏体转变 

分 类 号：TG139.6[一般工业技术—材料科学与工程]