A Study on Phase Transformation of Fine-grained TiNi and TiNiCu Shape Memory Alloys
Date Issued
2005
Date
2005
Author(s)
Lin, Kai-Nan
DOI
zh-TW
Abstract
Effects of grain size on transformation behavior and mechanical property of (1) Ti50Ni40Cu10 SMA thin plates with 40% cold rolling, (2) Ti51Ni49 SMA melt-spun ribbons and (3) Ti50Ni40Cu10 SMA rapid solidificated rods with recrystallization annealing are studied. When the annealing time is short, thermal energy contributes to release the residual stress and to eliminate the lattice defects. On the other hand, thermal energy contributes to recovery, recrystallization and grain growth when the annealing time is long. DMA test indicates that 40% cold-rolled Ti50Ni40Cu10 plates have high damping capacity (tanδ>0.04), especially for the plate annealed at 650oC×72hrs. Because of the coexistence of different size grains, Ti51Ni49 melt spinning ribbons reveal multiple martensitic transformation steps. During the annealing small grains show obviously growth but large ones don’t. Both 40% cold-rolled thin plates and rapid solidificated rods have the same property, i.e. their grain growth exponents increase with the increasing annealing temperature and they are consistent with Arrhenius diffusion model having the grain growth activation energies 306.47kJ/mol and 1653.4kJ/mol, respectively. According to this study, the major parameter affecting transformation behavior is the annealing temperature.
Subjects
TiNi基形狀記憶合金
冷輥壓
快速凝固
再結晶退火
麻田散體變態
制振能
TiNi shape memory alloys
cold rolling
rapid solidification
annealing
martensitic transformation
damping capacity
Type
thesis
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