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Characterization of mechanical and microstructural properties of constrained groove pressed nitinol shape memory alloy for biomedical applications.

Abstract

Among shape memory alloys, nitinol alloy is biocompatible in nature and thus widely used in bone tissue engineering, stents, dental and orthopedic implants. To improve mechanical properties and extend its application window, in this paper, the Ni50.5Ti49.5 (nitinol) sheets are processed by constrained groove pressing (CGP) process, which is one of the effective severe plastic deformation (SPD) techniques for refining microstructure and enhancing mechanical properties in sheet metals. The microstructure and X-ray diffraction studies of CGPed sheets show uniform grain refinement and increase in martensitic variant. Based on tensile and micro-hardness tests on water quenched (WQ) and CGPed nitinol alloy, the results show about up to 2.5 times increment in ultimate tensile strength and yield strength, significant enhancement in micro-hardness and change in strain hardening behavior. For characterizing the strain hardening behavior, Holloman and Voce models have been determined to have strong correlation with the experimental data for WQ and CGPed nitinol alloy respectively. Thus, nitinol alloy after CGP exhibits grain refinement and microstructural evolution, showing an increase in stress induced martensite phase which indicates superior mechanical properties such as high strength, uniform deformation regime and microhardness. These enhancements will help in reduction of other supporting materials generally used for improving structural integrity and load bearing capacity in biomedical applications of nitinol alloy.

Authors+Show Affiliations

Department of Mechanical Engineering, Birla Institute of Technology & Science (BITS), Pilani, Hyderabad Campus, Jawahar Nagar, Kapra Mandal, Medchal District, Telangana - 500 078, India. Electronic address: p20160421@hyderabad.bits-pilani.ac.in.Department of Mechanical Engineering, Birla Institute of Technology & Science (BITS), Pilani, Hyderabad Campus, Jawahar Nagar, Kapra Mandal, Medchal District, Telangana - 500 078, India.Department of Mechanical Engineering, Birla Institute of Technology & Science (BITS), Pilani, Hyderabad Campus, Jawahar Nagar, Kapra Mandal, Medchal District, Telangana - 500 078, India.Department of Mechanical Engineering, Birla Institute of Technology & Science (BITS), Pilani, Hyderabad Campus, Jawahar Nagar, Kapra Mandal, Medchal District, Telangana - 500 078, India.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31147045

Citation

Bhardwaj, Akhil, et al. "Characterization of Mechanical and Microstructural Properties of Constrained Groove Pressed Nitinol Shape Memory Alloy for Biomedical Applications." Materials Science & Engineering. C, Materials for Biological Applications, vol. 102, 2019, pp. 730-742.
Bhardwaj A, Gupta AK, Padisala SK, et al. Characterization of mechanical and microstructural properties of constrained groove pressed nitinol shape memory alloy for biomedical applications. Mater Sci Eng C Mater Biol Appl. 2019;102:730-742.
Bhardwaj, A., Gupta, A. K., Padisala, S. K., & Poluri, K. (2019). Characterization of mechanical and microstructural properties of constrained groove pressed nitinol shape memory alloy for biomedical applications. Materials Science & Engineering. C, Materials for Biological Applications, 102, pp. 730-742. doi:10.1016/j.msec.2019.04.070.
Bhardwaj A, et al. Characterization of Mechanical and Microstructural Properties of Constrained Groove Pressed Nitinol Shape Memory Alloy for Biomedical Applications. Mater Sci Eng C Mater Biol Appl. 2019;102:730-742. PubMed PMID: 31147045.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Characterization of mechanical and microstructural properties of constrained groove pressed nitinol shape memory alloy for biomedical applications. AU - Bhardwaj,Akhil, AU - Gupta,Amit Kumar, AU - Padisala,Shanthan Kumar, AU - Poluri,Kamal, Y1 - 2019/04/24/ PY - 2018/10/16/received PY - 2019/03/12/revised PY - 2019/04/22/accepted PY - 2019/6/1/entrez PY - 2019/5/31/pubmed PY - 2019/5/31/medline KW - Austenite KW - Constrained groove pressing KW - Martensite KW - Nitinol KW - Severe plastic deformation KW - Shape memory alloy SP - 730 EP - 742 JF - Materials science & engineering. C, Materials for biological applications JO - Mater Sci Eng C Mater Biol Appl VL - 102 N2 - Among shape memory alloys, nitinol alloy is biocompatible in nature and thus widely used in bone tissue engineering, stents, dental and orthopedic implants. To improve mechanical properties and extend its application window, in this paper, the Ni50.5Ti49.5 (nitinol) sheets are processed by constrained groove pressing (CGP) process, which is one of the effective severe plastic deformation (SPD) techniques for refining microstructure and enhancing mechanical properties in sheet metals. The microstructure and X-ray diffraction studies of CGPed sheets show uniform grain refinement and increase in martensitic variant. Based on tensile and micro-hardness tests on water quenched (WQ) and CGPed nitinol alloy, the results show about up to 2.5 times increment in ultimate tensile strength and yield strength, significant enhancement in micro-hardness and change in strain hardening behavior. For characterizing the strain hardening behavior, Holloman and Voce models have been determined to have strong correlation with the experimental data for WQ and CGPed nitinol alloy respectively. Thus, nitinol alloy after CGP exhibits grain refinement and microstructural evolution, showing an increase in stress induced martensite phase which indicates superior mechanical properties such as high strength, uniform deformation regime and microhardness. These enhancements will help in reduction of other supporting materials generally used for improving structural integrity and load bearing capacity in biomedical applications of nitinol alloy. SN - 1873-0191 UR - https://www.unboundmedicine.com/medline/citation/31147045/Characterization_of_mechanical_and_microstructural_properties_of_constrained_groove_pressed_nitinol_shape_memory_alloy_for_biomedical_applications L2 - https://linkinghub.elsevier.com/retrieve/pii/S0928-4931(18)33164-3 DB - PRIME DP - Unbound Medicine ER -