Porous TiNiCu ternary shape memory alloys （SMAs） were successfully fabricated by powder metallurgy method. The microstructure, martensitic transformation behavior, damping performance and mechanical properties of th...Porous TiNiCu ternary shape memory alloys （SMAs） were successfully fabricated by powder metallurgy method. The microstructure, martensitic transformation behavior, damping performance and mechanical properties of the fabricated alloys were intensively studied. It is found that the apparent density of alloys decreases with increasing the Cu content, the porous Ti50Ni40Cu10 alloy exhibits wide endothermic and exothermic peaks arisen from the hysteresis of martensitic transformations, while the porous Ti50Ni30Cu20 alloy shows much stronger and narrower endothermic and exothermic peaks owing to the B2-B19 transformation taking place easily. Moreover, the porous Ti50Ni40Cu10 alloy shows a lower shape recovery rate than the porous Ti50Ni50 alloy, while the porous Ti50Ni30Cu20 alloy behaves reversely. In addition, the damping capacity （or internal friction, IF） of the porous TiNiCu alloys increases with increasing the Cu content. The porous Ti50Ni30Cu20 alloy has very high equivalent internal friction, with the maximum equivalent internal friction value five times higher than that of the porous Ti50Ni50 alloy.展开更多
在美国Argonne国家实验室连接有IVEM-Tandem National Facility加速器的Hi-tatch3000电子显微镜上,通过400KeV Xe^+离子就位辐照研究了TiNiCu形状记忆合金的常温晶态-非晶态转变。入射的Xe离子通过级联碰撞,从0.05 dpa开始辐照诱发TiNiC...在美国Argonne国家实验室连接有IVEM-Tandem National Facility加速器的Hi-tatch3000电子显微镜上,通过400KeV Xe^+离子就位辐照研究了TiNiCu形状记忆合金的常温晶态-非晶态转变。入射的Xe离子通过级联碰撞,从0.05 dpa开始辐照诱发TiNiCu合金化学无序,非晶化过程和化学无序几乎同时进行;0.2dpa后,马氏体变体的衬度明显减小,变得非常模糊;在0.4dpa非晶化转变完成,马氏体变体的衬度完全消失。展开更多
The transformation behavior of a TiNiCu shape memory alloy electrolyticallycharged with hydrogen was investigated by means of different scanning calorimetry (DSC), opticalmicroscope and X-ray diffraction (XRD). The re...The transformation behavior of a TiNiCu shape memory alloy electrolyticallycharged with hydrogen was investigated by means of different scanning calorimetry (DSC), opticalmicroscope and X-ray diffraction (XRD). The results showed that inter- and inner-granular hydridesformed after charging with hydrogen, and the hydrides suppressed martensitic transformation. Theelectrolytically charged hydrogen can be easily released by heat treatment and the transformationoccurred again, which was verified by the DSC and XRD experiments.展开更多
The effect of heat treatment on the phase transformation behavior of TiNiCu shape memory alloy wires and the temperature memory effect in this alloy were investigated by the resistance method. These results showed tha...The effect of heat treatment on the phase transformation behavior of TiNiCu shape memory alloy wires and the temperature memory effect in this alloy were investigated by the resistance method. These results showed that with increasing annealing temperature and annealing time, the phase transformation temperatures of TiNiCu wires were shifted to higher temperatures in the heating and cooling process. It was also found that incomplete thermal cycles, upon heating the TiNiCu wires, which were arrested at a temperature between the start and finish temperatures of the reverse martensite transformation, could induce a kinetic stop in the next complete thermal cycle. The kinetic stop temperature was closely related to the previous arrested temperature. This phenomenon was defined as the temperature memory effect. The result of this study was consistent with the previous report on the phenomenon obtained using the differential scanning calorimetry method, indicating that temperature memory effect was a common phenomenon in shape memory alloys.展开更多
Both sputtering conditions and crystallizing temperatures have great influence on the microstructures and phase transformation characteristics for Ti 51 Ni 44Cu 5. By means of the resistance temperature measurement, X...Both sputtering conditions and crystallizing temperatures have great influence on the microstructures and phase transformation characteristics for Ti 51 Ni 44Cu 5. By means of the resistance temperature measurement, X ray diffraction and atomic fore microscopic study, the results indicate that the transformation temperatures of the thin films increase and the "rock candy" martensitic relief is more easily obtained with promoting the sputtering Ar pressure, sputtering power, or crystallizing temperature. However, when sputtering Ar pressure, sputtering power, or crystallizing temperature are lower, a kind of "chrysanthemum" relief, which is related with Ti rich GP zones, is much easier to be observed. The reason is that during crystallization process, both of the inherent compressive stresses introduced under the condition of higher sputtering pressure or higher crystallizing temperature are helpful to the transition from GP zones to Ti 2(NiCu) precipitates and the increase of the transformation temperatures. The addition of copper to substitute for 5% nickel in mole fraction can reduce the transformation hysteresis width to about 10 ～ 15?℃.展开更多
基金Projects(50871039,51205135)supported by the National Natural Science Foundation of ChinaProject(S2011040001436)supported by the Guangdong Provincial Natural Science Foundation,China
文摘Porous TiNiCu ternary shape memory alloys （SMAs） were successfully fabricated by powder metallurgy method. The microstructure, martensitic transformation behavior, damping performance and mechanical properties of the fabricated alloys were intensively studied. It is found that the apparent density of alloys decreases with increasing the Cu content, the porous Ti50Ni40Cu10 alloy exhibits wide endothermic and exothermic peaks arisen from the hysteresis of martensitic transformations, while the porous Ti50Ni30Cu20 alloy shows much stronger and narrower endothermic and exothermic peaks owing to the B2-B19 transformation taking place easily. Moreover, the porous Ti50Ni40Cu10 alloy shows a lower shape recovery rate than the porous Ti50Ni50 alloy, while the porous Ti50Ni30Cu20 alloy behaves reversely. In addition, the damping capacity （or internal friction, IF） of the porous TiNiCu alloys increases with increasing the Cu content. The porous Ti50Ni30Cu20 alloy has very high equivalent internal friction, with the maximum equivalent internal friction value five times higher than that of the porous Ti50Ni50 alloy.
文摘在美国Argonne国家实验室连接有IVEM-Tandem National Facility加速器的Hi-tatch3000电子显微镜上,通过400KeV Xe^+离子就位辐照研究了TiNiCu形状记忆合金的常温晶态-非晶态转变。入射的Xe离子通过级联碰撞,从0.05 dpa开始辐照诱发TiNiCu合金化学无序,非晶化过程和化学无序几乎同时进行;0.2dpa后,马氏体变体的衬度明显减小,变得非常模糊;在0.4dpa非晶化转变完成,马氏体变体的衬度完全消失。
基金This project is financially supported by the National Natural Science Foundation of China (No.10175042) and by the Pro-gram for New Century Excellent Talents in Universities.
文摘The transformation behavior of a TiNiCu shape memory alloy electrolyticallycharged with hydrogen was investigated by means of different scanning calorimetry (DSC), opticalmicroscope and X-ray diffraction (XRD). The results showed that inter- and inner-granular hydridesformed after charging with hydrogen, and the hydrides suppressed martensitic transformation. Theelectrolytically charged hydrogen can be easily released by heat treatment and the transformationoccurred again, which was verified by the DSC and XRD experiments.
文摘The effect of heat treatment on the phase transformation behavior of TiNiCu shape memory alloy wires and the temperature memory effect in this alloy were investigated by the resistance method. These results showed that with increasing annealing temperature and annealing time, the phase transformation temperatures of TiNiCu wires were shifted to higher temperatures in the heating and cooling process. It was also found that incomplete thermal cycles, upon heating the TiNiCu wires, which were arrested at a temperature between the start and finish temperatures of the reverse martensite transformation, could induce a kinetic stop in the next complete thermal cycle. The kinetic stop temperature was closely related to the previous arrested temperature. This phenomenon was defined as the temperature memory effect. The result of this study was consistent with the previous report on the phenomenon obtained using the differential scanning calorimetry method, indicating that temperature memory effect was a common phenomenon in shape memory alloys.
文摘Both sputtering conditions and crystallizing temperatures have great influence on the microstructures and phase transformation characteristics for Ti 51 Ni 44Cu 5. By means of the resistance temperature measurement, X ray diffraction and atomic fore microscopic study, the results indicate that the transformation temperatures of the thin films increase and the "rock candy" martensitic relief is more easily obtained with promoting the sputtering Ar pressure, sputtering power, or crystallizing temperature. However, when sputtering Ar pressure, sputtering power, or crystallizing temperature are lower, a kind of "chrysanthemum" relief, which is related with Ti rich GP zones, is much easier to be observed. The reason is that during crystallization process, both of the inherent compressive stresses introduced under the condition of higher sputtering pressure or higher crystallizing temperature are helpful to the transition from GP zones to Ti 2(NiCu) precipitates and the increase of the transformation temperatures. The addition of copper to substitute for 5% nickel in mole fraction can reduce the transformation hysteresis width to about 10 ～ 15?℃.
