Annealing behavior and shape memory effect in NiTi alloy processed by equal-channel angular pressing at room temperature

作者：Shahmir, Hamed^*; Nili-Ahmadabadi, Mahmoud; Wang, Chuan Ting; Jung, Jai Myun; Kim, Hyoung Seop; Langdon, Terence G.

来源：Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 2015, 629: 16-22.

DOI：10.1016/j.msea.2015.01.072

• Shape memory effect
• Equal-channel angular pressing
• NiTi shape memory alloys
• Ultrafine-grained materials

A martensitic NiTi shape memory alloy was processed successfully by equal-channel angular pressing (ECAP) for one pass at room temperature using a core-sheath billet design. The annealing behavior and shape memory effect of the ECAP specimens were studied followed by post-deformation annealing (PDA) at 673 K for various times. The recrystallization and structural evolution during annealing were investigated by differential scanning calorimetry, dilatometry, X-ray diffraction, transmission electron microscopy and microhardness measurements. The results indicate that the shape memory effect improves by PDA after ECAP processing. Annealing for 10 mm gives a good shape memory effect which leads to a maximum in recoverable strain of 6.9 pct upon heating where this is more than a 25 pct improvement compared with the initial state.

• 出版日期2015-4-1
• 单位南京理工大学