Nam Tae-hyun, Yu Cheol-am, Nam Jung-min, Kim Hyun-gon, Kim Yeon-wook
Division of Advanced Materials Engineering, Center for I-cube and ERI, Gyeongsang National University, Jinju 660-701, Korea.
J Nanosci Nanotechnol. 2008 Feb;8(2):722-7. doi: 10.1166/jnn.2008.d260.
Microstructures and deformation behaviour of Ti-45Ni-5Cu and Ti-46Ni-5Cu alloy ribbons prepared by melt spinning were investigated by transmission electron microscopy, thermal cycling tests under constant load and tensile tests. Spherical Ti2Ni particles coherent with the B2 parent phase were observed in the alloy ribbons when the melt spinning temperature was higher than 1773 K. Average size of Ti2Ni particles in the ribbons obtained at 1873 K was 8 nm, which was smaller than that (10 nm) in the ribbons obtained at 1773 K. Volume fraction of Ti2Ni phase in the ribbons obtained at 1873 K was 40%, which was larger than that (20%) in the ribbons obtained at 1773 K. The stress required at temperatures of Af + 10 K for the stress-induced martensitic transformation increased from 93 MPa to 229 MPa and apparent elastic modulus of the B2 parent phase increased from 56 GPa to 250 GPa with increasing the melt spinning temperature from 1673 K to 1873 K in Ti-45Ni-5Cu alloy ribbons. The critical stress for slip deformation of the ribbons increased by coherent Ti2Ni particles, and thus residual elongation did not occur even at 160 MPa, while considerable plastic deformation occurred at 60 MPa in the ribbons without Ti2Ni particles. Almost perfect superelastic recovery was found in the ribbons with coherent Ti2Ni particles, while only partial superelastic recovery was observed in the ribbons without coherent Ti2Ni particles.
通过透射电子显微镜、恒载热循环试验和拉伸试验，研究了采用熔体纺丝制备的Ti-45Ni-5Cu和Ti-46Ni-5Cu合金薄带的微观结构和变形行为。当熔体纺丝温度高于1773 K时，在合金薄带中观察到与B2母相相干的球形Ti2Ni颗粒。在1873 K获得的薄带中Ti2Ni颗粒的平均尺寸为8 nm，小于在1773 K获得的薄带中的尺寸（10 nm）。在1873 K获得的薄带中Ti2Ni相的体积分数为40%，大于在1773 K获得的薄带中的体积分数（20%）。在Ti-45Ni-5Cu合金薄带中，随着熔体纺丝温度从1673 K升高到1873 K，应力诱发马氏体相变在Af + 10 K温度下所需的应力从93 MPa增加到229 MPa，B2母相的表观弹性模量从56 GPa增加到250 GPa。相干的Ti2Ni颗粒使薄带的滑移变形临界应力增加，因此即使在160 MPa时也不会发生残余伸长，而在没有Ti2Ni颗粒的薄带中，在60 MPa时会发生相当大的塑性变形。在具有相干Ti2Ni颗粒的薄带中发现了几乎完美的超弹性恢复，而在没有相干Ti2Ni颗粒的薄带中仅观察到部分超弹性恢复。
