Effect of Strain Rates on the Transformation Behavior of Ni-Ti Alloy
| Autor: | Hidefumi Date |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Universal testing machine
Materials science Mechanical Engineering Metallurgy Split-Hopkinson pressure bar Slip (materials science) Strain rate Condensed Matter Physics Differential scanning calorimetry Mechanics of Materials Martensite Pseudoelasticity General Materials Science Deformation (engineering) Composite material |
| Zdroj: | Materials Science Forum. :3231-3236 |
| ISSN: | 1662-9752 |
| DOI: | 10.4028/www.scientific.net/msf.539-543.3231 |
| Popis: | In order to clarify the effect of strain rates on phase transformation behaviors of Ni-Ti alloy, a compressive test using a cylindrical specimen of polycrystalline Ni-Ti alloy of Ti-50.69 at% Ni was carried out at a high strain rate and a low strain rate. The transformation temperatures were determined by a differential scanning calorimeter (DSC) using a sample cut from a compressed specimen. The transformation temperatures of the specimens before deformation were Ms= 303 K, Mf = 287 K, As = 297 K and Af = 319 K, respectively. The compressive test was carried out using specimen heated from liquid nitrogen temperature to room temperature. A universal testing machine as a static test apparatus and a Split Hopkinson Bar apparatus for a dynamic test were used. The specimen had a reoriented martensite phase after deformation because the superelastic effect was not observed upon unloading. Two reverse transformations during heating and a forward transformation during cooling were observed by DSC measurement. The first reverse transformation corresponds to that of thermal-induced martensite by immersion in liquid nitrogen and the second reverse transformation corresponds to that of reoriented martensite with slips in a polycrystalline matrix introduced by plastic deformation. The reverse transformation of the martensite phase with a slip exhibited strong strain rate dependency. Plastic strains and strain rate had strong influence on the shape recovery. The interaction between the temperature elevation by a conversion of plastic work and slip generated by dynamic plastic deformation is a complicated problem. |
| Databáze: | OpenAIRE |
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