| Title |
Effect of Heat Treatment on the Transformation Characteristics and Preferred Orientation in TiNiCu Thin Plate SMA Prepared by Rapid Solidification Process |
| Authors |
권순일(Soon Il Kwon) ; 김선진(Seon Jin Kim) ; 이규환(Kyu Hwan Lee) ; 신명철(Myung Chul Shin) |
| Abstract |
50Ti-40Ni-IOCu(at%) and 50Ti-46Ni-4Cu(at.%) shape memory alloy(SMA) ribbons were prepared by melt spinning method. Using differential scanning calorimeter(DSC), X-ray diffractometer, optical microscope, and thermal cycling test under constant load(strain-temp. measurement), the effect of annealing temperature on the phase transformation and the shape memory behavior of melt-spun has been investigated at temperatures between 400℃ and 700℃. From thermal cyclic test in the Ti_So Ni_(40)Cu_(10) ribbon two-step martensitic transformation is clearly observed, while in the Ti_(10)Ni_(46)Cu₄ ribbon one-step martensitic transformation takes place. Transformation hysteresis(ΔT=A-M) of Ti_(50)Ni_(40)Cu_(10) alloys is still more narrow than that of alloys added 4at.%Cu. Rapidly solidified TiMiCu shape memory ribbon has good crystallinity and preferred orientation. And its preferred orientation is associated with the transformation strain. As the annealing temperature increases, the shape of grain changes to lath-shaped grains along the direction of width and transformation strain decreases. It was confirmed that transformation strain clearly increases with increasing the number of fine equiaxed grains and preferred orientation. |