HREM studies of twin boundary structure in deformed martensite in the cold-rolled TiNi shape memory alloy

Rolling texture of α"(C-orthorhombic) martensite phase in Ti-22mol%Nb-3mol%Al β-titanium based shape memory alloy was examined using X-ray pole figure measurement. The alloy was dual phase of α'' and β(bcc) at room temperature (RT) and was cold-rolled with reduction rates of 40%~99% at RT. Stress-induced martensitic transformation occurred during the rolling and then the material was fully transformed into martensite phase. Subscript α" and β indicate martensite and parent phase hereafter. The major texture was close to {411}α"<173>α" when the reduction rate was lower than 60%. This texture is a result of a preferential formation of specific variants which have a higher interaction with the macroscopic deformation. As the reduction rate was increased, ND moved toward {101}α" whereas RD was around <010>α" regardless of the reduction rate. {101}α"<010>α" texture was confirmed when the reduction rate was 99%.

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Large internal stress-assisted twin-boundary motion in Ni2MnGa ferromagnetic shape memory alloy

Applied Physics Letters ◽

10.1063/1.3645626 ◽

2011 ◽

Vol 99 (14) ◽

pp. 141907 ◽

Cited By ~ 4

Author(s):

Z. H. Nie ◽

D. Y. Cong ◽

D. M. Liu ◽

Y. Ren ◽

M. Pötschke ◽

...

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Internal Stress ◽

Twin Boundary ◽

Boundary Motion ◽

Ferromagnetic Shape Memory Alloy ◽

Ferromagnetic Shape Memory

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Textures in cold-rolled and annealed Ti50Ni50 shape memory alloy

Scripta Materialia ◽

10.1016/j.scriptamat.2004.01.009 ◽

2004 ◽

Vol 50 (7) ◽

pp. 937-941 ◽

Cited By ~ 37

Author(s):

S.H. Chang ◽

S.K. Wu

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Cold Rolled

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Type II Twin Boundary Structure of Martensite in Ti-Ni and Ti-Pd Shape Memory Alloys

Materia Japan ◽

10.2320/materia.37.386 ◽

1998 ◽

Vol 37 (5) ◽

pp. 386-386

Author(s):

Minoru Nishida

Keyword(s):

Shape Memory Alloys ◽

Shape Memory ◽

Twin Boundary ◽

Boundary Structure ◽

Type Ii

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Damping Characteristics of Cold-Rolled and Annealed Equiatomic TiNi Shape Memory Alloy

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.319.9 ◽

2006 ◽

Vol 319 ◽

pp. 9-16 ◽

Cited By ~ 10

Author(s):

S.H. Chang ◽

Shi Kang Wu

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Storage Modulus ◽

Damping Capacity ◽

Damping Characteristics ◽

Annealing Conditions ◽

Cold Rolled ◽

Tan Δ ◽

Short Time ◽

And Storage

Damping capacity and storage modulus of cold-rolled and annealed Ti50Ni50 SMA are systematically investigated by DSC and DMA tests. The specimens annealed at 500 oC for 1 ~ 72 h and annealed at 650 oC for short time can all reach a high tan δ value and a deep storage modulus minimum during B2→R transformation. This reveals that the occurrence of R-phase can strongly soften the storage modulus and thus promote the damping capacity of Ti50Ni50 SMA. The specimens anneaed at 650 oC for longer time have a lower tan δ value due to the diminishing of R-phase formation. Therefore, a good damping capacity associated with a significant softening storage modulus can be acquired by suitably control the annealing conditions of cold-rolled Ti50Ni50 to generate adequate of R-phase premartensite.

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