Shape memory effect of NiTi alloy processed by equal-channel angular pressing followed by post deformation annealing

6th International Conference on Nanomaterials by Severe Plastic Deformation

材料科学;化学

Shahmir, Hamed^1 ; Nili-Ahmadabadi, Mahmoud^1 ; Langdon, Terence G.^2,3

School of Metallurgy and Materials, College of Engineering, University of Tehran, Tehran, Iran^1

Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ, United Kingdom^2

Departments of Aerospace and Mechanical Engineering and Materials Science, University of Southern California, Los Angeles CA 90089-1453, United States^3

关键词: Bulk samples;    Core sheaths;    Elevated temperature;    Microhardness measurement;    NiTi alloys;    NiTi shape memory alloys;    Post-deformation annealing;    Structural evolution;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/63/1/012111/pdf
DOI  :  10.1088/1757-899X/63/1/012111

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

Processing by Equal-Channel Angular Pressing (ECAP) is generally considered superior to most other SPD techniques because it uses relatively large bulk samples. However, due to their low deformability it has proven almost impossible to successfully process NiTi alloys by ECAP at room temperature and therefore the processing is conducted at elevated temperatures. Recently, a new billet design was introduced and it was used to achieve the successful processing of NiTi shape memory alloys by ECAP. In this procedure, a NiTi alloy was inserted as a core within an Fe sheath to give a core-sheath billet. In this research, a NiTi was processed by one pass ECAP with this new billet design at room temperature. The structural evolution during annealing was investigated by X-ray diffraction (XRD) and microhardness measurements. Post deformation annealing (PDA) was carried out at 400°C for 5 to 300 min and the results indicate that the shape memory effect improves by PDA after ECAP.