Microdefects and electron densities in NiTi shape memory alloys studied by positron annihilation
来源期刊：中国有色金属学报(英文版)2006年第6期
论文作者：胡益丰 邓文 郝文博 岳丽 黄乐 黄宇阳 熊良钺
文章页码：1259 - 1262
Key words：NiTi alloy; microdefect; electron density; martensite transformation
Abstract: The microdefects and free electron densities in B2, R and B19′ phases of Ni50.78Ti49.22 alloy were studied by positron lifetime measurements. Comparing the lifetime parameters of the Ni50.78Ti49.22 alloy measured at 295 K and 225 K, 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 of the R phase is larger, while the concentration of these defects is lower than that of the B2 phase. The Ni50.78Ti49.22 alloy exhibits B19′ phase at 115 K. In comparison with the R phase, the free electron density of the B19′ phase increases, the open volume of the defects of the B19′ phase reduces, and the concentration of these defects increases. The microdefects and the free electron density play an important role during the multi-step transformations (B2→R→B19′ phase transformations) in Ni50.78Ti49.22 alloy with the decrease of temperature.
基金信息：the National Natural Science Foundations of China
the Natural Science Foundation of Guangxi Province, China
