Effect of Deformation Induced Transformation in B2-Type TiNi Alloys.

B2 型 TiNi 合金中变形诱发相变的影响。

基本信息

批准号：
09650723
负责人：
NISHIDA Minoru
金额：
$ 1.86万
依托单位：
Kumamoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

Ti-Ni alloys of near-equiatomic composition exhibit the shape memory properties associated with thermoelastic martensitic transformation. The other peculiar characteristic is anomalous ductility around room temperature in both B2 parent and B19' martensite phases. The ductility of Ti-Ni alloys is about 40 to 60% in tensile elongation below Mssiguma which is upper limit temperature for the formation of stress induced martensite. The ductility is reduced to 30% above Mssiguma. The stress-strain curves of martensite is divided into three stages. The de-twinning of <011> Type II twin and the formation of (100) compound twin are observed in the first stage. The deformation mode in second and third stages is not only slip deformation but also twinning deformation with the (100), (001) and (20-1) compound twins. The ductility of the B19' martensite is attributable to the formation of (20-1) twin with large twinning shear of 0.4250 and the increment of independent slip system due to the formation of the three compound twins. The essentially same microstructures are developed at Ms to Mssiguma. Above Mssiguma, strain induced martensite is formed in B2 parent phase by tensile deformation. However, the martensite is not grown with increasing the strain. The Ti-Ni alloys exhibit good ductility at the temperature range where the martensite is stable. Goo et al., have suggested that the ductility of the Ti-Ni with B2 structure is attributable to the formation of {114} B2 compound twinning. In the present study, this twinning is derived from the (20-1)B19' twinning. That is, the (20-1)B19' twinning is remained as the {114}B2 compound twinning after reverse transformation. This Is consistent with the lattice correspondence between B2 parent phase and B19' martensite phase. Therefore, the anomalous ductility of B2-type Ti-Ni alloys around room temperature is related to the stress induced martensite.

近距离组合物的Ti-Ni合金表现出与热弹性马氏体转化相关的形状记忆特性。另一个特点是B2父和B19'Martensite阶段围绕室温的异常延展性。 Ti-Ni合金的延展性约为Mssiguma以下的拉伸伸长率的40％至60％，这是压力诱导的Martensite的上限温度。延展性降低到高于mssiguma的30％。马氏体的应力 - 应变曲线分为三个阶段。在第一阶段观察到<011> II型双胞胎的脱扭态和（100）化合物双胞胎的形成。第二阶段和第三阶段的变形模式不仅是滑移变形，而且还具有（100），（001）和（20-1）化合物双胞胎的双重变形。 B19'Martensite的延展性归因于（20-1）双胞胎的形成，其大的双链剪切为0.4250，并且由于形成了三个化合物双胞胎，因此延伸的独立滑移系统的增加。基本相同的微观结构是在MSSiguma上开发的。在Mssiguma上方，菌株诱导的Martensite是通过拉伸变形在B2父相中形成的。但是，马氏体不会随着菌株的增加而生长。 Ti-Ni合金在马氏体稳定的温度范围内表现出良好的延展性。 Goo等人建议，具有B2结构的Ti-Ni的延展性归因于{114} B2化合物孪生的形成。在本研究中，这种双胞胎源自（20-1）B19'双胞胎。也就是说，（20-1）B19'双胞胎在反向转换后保持为{114} B2化合物双胞胎。这与B2父相和B19'Martensite相之间的晶格对应关系一致。因此，B2型Ti-Ni合金围绕室温的异常延展性与应力诱导的马氏体有关。