Effects of Cerium Addition on Martensitic Transformation and Microstructure of Ti<SUB>49.3</SUB>Ni<SUB>50.7</SUB> Alloy

Abstract

In order to study the effect of Cerium on martensitic transformation and microstructure of Ti 49:3 Ni 50:7 alloy, a group of TiNiCe alloys with different content of Ce addition were prepared. The microstructure and the martensitic transformation behavior of TiNiCe ternary alloys were investigated by optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results show that the microstructure of Ti 49:3 Ni 50:7 alloy is changed obviously by Ce addition, and there are many Ce-rich phases dispersing in the TiNi matrix. One step martensitic transformation due to B2 $ B19 0 transformation occurs during the cooling and heating processes of the TiNiCe ternary alloys. The phase transformation temperatures increase remarkably when the content of Ce is less than 2 at%. However, when the content of Ce is further increasing, the phase transformation temperatures increase slowly and tend to stable.

Microstructure and Phase Transformation Analysis of Ni50−xTi50Lax Shape Memory Alloys

“…The normalized pixel amounts of bright and dark precipitates exhibit an increasing tendency, which indicates that the size and quantity of bright and black precipitates increase with increasing La content in Ni 50−x Ti 50 La x alloys. This case is highly similar to the morphologies of Ni-Ti-Ce [10], Ni-Ti-Gd [11], Ni-Ti-Dy [12], and Ni-Ti-Y [13] alloys. The types and amounts of precipitates in Ti-Ni-based shape memory alloys can significantly affect their phase transformation behavior [15].…”

“…The microstructure of Ni 50 Ti 50−x La x (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9) alloys was found to consist of LaNi precipitates and near-equiatomic TiNi matrix. The martensitic transformation start temperatures decrease gradually with increasing La content, contrary to the behavior found in Ni-Ti-Ce [10], Ni-Ti-Gd [11], Ni-Ti-Dy [12], and Ni-Ti-Y [13] alloys. This difference is attributed to the decrease of Ti content because of the increase of La content in Ni 50 Ti 50−x La x alloys.…”

“…The resulting microstructure and martensitic transformation behavior observed from addition of RE elements such as Ce [10], Gd [11], Dy [12], and Y [13] to Ti-Ni alloys have been studied, and results show that Ti-Ni-RE alloys consist of a binary TiNi matrix, RENi precipitate, and Ti 2 Ni precipitate. The martensitic transformation temperature generally increases with increasing RE content [10][11][12][13]. In other words, adding RE elements to Ti-Ni alloys to replace Ni content can increase the martensitic transformation temperature.…”

Structure, phase transformation, and hardness of NiTiHfNd alloys

“…Rare earth (RE) elements such as Ce [15], Gd [16], Dy [17], Nd [18], La [19] and Pr [20] have also been added to binary NiTi alloys to tune the phase transformation properties. The addition of Ce, Gd, and Dy to NiTi alloy increased the phase transformation temperatures because of some new-type second precipitates that exist in the NiTiRE alloys, which change the Ni/Ti ratio of the matrix [21].…”

Effect of Nd Addition on the Microstructure and Martensitic Transformation of Ni-Ti Shape Memory Alloys

“…Moreover, the microstructure and martensitic transformation temperature of the rare earth (RE) of Ce [6], Gd [7], Dy [8], and La [9] in addition to Ni-Ti binary alloys have also been studied using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The addition of these REs to Ni-Ti binary alloys was found to increase the martensitic transformation temperature and change the phase transformation sequence.…”