Effects of Nb Content on Yield Strength of NiTiNb Alloys in Martensite State
Two near single-phase NiTiNb alloys-Ni_(50)Ti_(48)Nb_2 and Ni_(49.5)Ti_(46.5)Nb_4-are prepared and studied by means of scanning elec-tron microscopy (SEM), energy dispersive spectroscopy (EDS), differential scanning calorimetry (DSC) and tensile tests in order to unearth the effects of Nb-atom solid solution in NiTi phase on the yield strength induced by self-accommodation of martensite variants. The results show that the yield strength of near single-phase NiTiNb alloys varies inversely with the amount of Nb-atoms solid-dissolved in NiTi phase. From the results out of the prior and current studies, it can be surmised that the effects of Nb content on the yield strength of NiTiNb alloys in martensite state depend on the coaetion. Nb solid solution weakening mechanism and β-Nb phase composite strengthening mechanism. This inference might be a satisfactory explanation to the fact that the yield strength of (NiTi)_(50-0.5x)Nb_x alloys in martensite state begins with decline and then rises when the Nb content in-creases.
作 者： Xiao Fu Ma Guojun Zhao Xinqing Xu Huibin 作者单位： School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191, China 刊 名： 中国航空学报（英文版） ISTIC 英文刊名： CHINESE JOURNAL OF AERONAUTICS 年，卷(期)： 2009 22(6) 分类号： V2 关键词： NiTiNb alloy martensite yield strength Nb content