The Shape-Memory Effect in a Titanium-35 wt.-% Niobium Alloy
1971; Taylor & Francis; Volume: 5; Issue: 1 Linguagem: Inglês
10.1179/030634571790439658
ISSN0026-0681
Autores Tópico(s)Intermetallics and Advanced Alloy Properties
ResumoAbstractAbstractThe shape-memory effect has been studied in a titanium −35 wt.-% niobium alloy. The effect is observed under two different sets of conditions. First, when the fully martensitic alloy is deformed below Ms it recovers its original shape when heated above As Secondly, if the alloy is deformed between Ms and As (with Ms artificially depressed by a fine dispersion of ω-phase precipitates, which prevents the martensite forming on cooling through the expected Ms , a strain-induced martensite is formed and on heating above As the deformation is recovered. When the orthorhombic martensite forms from the cubic β phase, there is an expansion of the unit cell along two axes of the orthorhombic and a contraction along the third. The orientation relationship between the two phases predicts 12 possible variants and on stressing that variant will be formed which results in a relief of the stress, e.g. under a tensile stress those lattice planes with an increased spacing in the orthorhombic phase will tend to lie perpendicular to the stress axis. Deformation below Ms causes growth of certain variants at the expense of others and deformation between Ms and Ms results in different variants being produced under different stress conditions.
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