A NEW CLASS OF METAL NANOCOMPOSITES WITH SUPERIOR MECHANICAL PROPERTIES: UNUSUAL THERMAL EXPANSION IN NbTi-NANOWIRES / NiTi-MATRIX COMPOSITE

摘要

An in-situ composite composed of NbTi nanowires, which are well dispersed and aligned in amorphousanocrystalline NiTi matrix, exhibits an unusual non-linear thermal expansion behavior during heating from 25 ℃ to 600 ℃. The evolution of the structure of NiTi matrix and the axial thermal expansion property of NbTi nanowires during heating process were studied by in situ synchrotron X-ray diffraction. The collective effects of the intrinsic thermal expansion properties of NiTi matrix and NbTi nanowires, and the coupling between nanowires and matrix during heating were responsible for the unusual thermal expansion behavior. The unusual non-linear thermal expansion property may have potential applications, such as thermal actuator, sensor and fastener materials.