Deformation Mechanism and Stabilization of Martensite in TiNi Shape Memory Alloy

• 作 者: Koichi Tsuchiya Minoru Umemoto
• 机 构: Structural Functions Research Group,Innovative Materials Engineering Laboratory,National Institute f
• 出 处: Journal of Materials Science & Technology
• 发表日期: 2010年10期
• 关键词: stabilization martensite deformed attributed stored tensile twins heating reason

The deformed microstructures of a TiNi shape memory alloy were investigated in present study to clarify the deformation mechanism.It is found that the stress-strain curve was divided into three stages based on the deformation modes.The cause of martensitic stabilization effect was also interpreted by paying special attention to the deformed microstructures.Transmission electron microscopic examination revealed that at the early stage of deformation martensitic reorientation and compound twinning relieved some of the elastic strain energy stored in martensite,and this contributes to the martensitic stabilization effect.However,when deformation strain became larger,the density of dislocations increased correspondingly.Antiphase boundaries were also found.The degree of ordering was therefore decreased due to dislocations and antiphase boundaries.So disordering was another cause of martensitic stabilization effect.In the middle stage of deformation martensitic stabilization was attributed to the two reasons above.

The deformed microstructures of a TiNi shape memory alloy were investigated in present study to clarify the deformation mechanism. It is found that the stress-strain curve was divided into three stages based on the deformation mode.. The cause of martensitic stabilization effect was also interpreted by paying special attention to the deformed microstructures. Transmission electron microscopic examination revealed that at the early stage of deformation martensitic reorientation and compound twinning relieved some of the elastic strain energy stored in martensite, and this contributes to the martensitic stabilization effect. However when deformation strain became larger, the density of dislocations increased correspondingly. Anti-segmentation was also found the degree of ordering was caused decreased due due to dislocations and antiphase boundaries. Disordering was another cause of martensitic stabilization effect. In the middle stage of deformation martensitic stong was attributedto the two reasons above.