Amorphization/Nanocrystallization of Shape Memory Alloys and Mechanism of Phase Transformation

形状记忆合金的非晶化/纳米化及相变机制

• 批准号: 17360312
• 负责人: TSUCHIYA Koichi
• 金额: $ 8.58万
• 依托单位: Toyohashi University of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2005
• 资助国家: 日本
• 起止时间: 2005 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17360312/
• 关键词: shape memory alloys; superelasticity; severe plastic deformation; amorphous; nanocrystalline; dislocations; twins; martensitic transformation

TiNi shape memory alloy has been used in diverse areas of applications. Recently the application is expanding in the field of medical devices such as guide wires and stents due to the development of minimally invasive surgery. It is also know that the TiNi undergoes crystalline-to-amorphous transformation by severe plastic deformations. In the present investigation, the process of amorphization/nanocrystallization by various methods of severe plastic deformation, including cold rolling, high pressure torsion and shot peening, was investigated by TEM observations.It was revealed that the B19' martensite reverts to B2 phase by plastic deformation and it transformed to amorphous by further deformation. Peculiar lamellar structures composed of alternative layers of amorphous and B2 crystalline phase. It was also found that the B2 layers on both sides of amorphous layers possess the almost identical crystallographic orientation. This indicates that the defect accumulation at the variant boundaries is responsible for the amorphization.For comparison, Zr-Cu alloys with various compositions were deformed by HPT. Only Zr_<50>Cu_<50> exhibited amorphization. The alloy was in B19' phase and has the fine martensitic twin structure before deformation. Thus it can be inferred that the fine twin structure promotes the accumulation of dislocations and invoke amorphization.

TiNi形状记忆合金已被广泛应用于各个领域。近年来，由于微创手术的发展，其在诸如导丝和支架等医疗器械领域的应用正在扩大。还知道TiNi通过剧烈的塑性变形经历晶体到非晶的转变。通过TEM观察，研究了冷轧、高压扭转和喷丸等强塑性变形方式下B19'马氏体的非晶化/纳米晶化过程，发现B19'马氏体经塑性变形后回复为B2相，进一步变形后转变为非晶。由非晶相和B2晶相交替层组成的特殊层状结构。研究还发现，非晶层两侧的B2层具有几乎相同的晶体学取向。结果表明，不同成分的Zr-Cu合金在高压形变过程中发生了非晶化，这与晶界缺陷的积累有关。只有Zr_<50>Cu_<50>（1-x）表现出非晶化。变形前合金为B19'相，具有细小的马氏体孪晶组织。因此，可以推断，细小的孪晶结构促进了位错的积累，引起了非晶化。

项目成果

TEM Observations of Nanostructured TiNi Shape Memory Alloy Produced by Severe Plastic Deformation

剧烈塑性变形产生的纳米结构 TiNi 形状记忆合金的 TEM 观察

• 发表时间: 2006
• 期刊: Proceedings of 16^<th> International Microscopy Congress
• 作者: K.Tsuchiya;et al.;K.Tsuchiya et al.
• 通讯作者: K.Tsuchiya et al.

Surface Amorphization of TiNi Shape Memory Alloy by Shot Peening

TiNi形状记忆合金喷丸表面非晶化

• 发表时间: 2005
• 期刊: J.Metastable and Nanocrystalline Solids 24-25
• 作者: K.Tsuchiya;H.Nakayama;Y.Todaka;M.Umemoto;K.Morii
• 通讯作者: K.Morii

Effect of Shot Peening on Surface Amorphization of TiNi Shape Memory Alloys

喷丸对TiNi形状记忆合金表面非晶化的影响

• 发表时间: 2006
• 期刊: J.Japan Inst.Metals 70
• 作者: TAKAHASHI;Yasuo;Q.Cao et al.
• 通讯作者: Q.Cao et al.

Martensitic Transformation and Mechanical Behavior of TiNi Shape Memory Alloys after Severe Plastic Deformation

TiNi形状记忆合金剧烈塑性变形后的马氏体相变及力学行为

• 发表时间: 2006
• 期刊: Mater. Sci. Forum 503-504
• 作者: K.Tsuchiya;et al.
• 通讯作者: et al.

TiNi系形状記憶合金の表層非晶質化/ナノ結晶化に与えるショットピーニング条件の影響

喷丸条件对TiNi基形状记忆合金表面非晶/纳米晶化的影响

• 发表时间: 2006
• 期刊: J. Japan Inst. Metals(日本金属学会誌) 70
• 作者: K.Tsuchiya;et al.;高橋 康夫;Takahashi Yasuo;曹 奇峰ら
• 通讯作者: 曹 奇峰ら