Effect of pre-strain on microstructure of Ni–Ti orthodontic archwires

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 473; no. 1; pp. 42 - 48
• Main Authors: Jafari, J., Zebarjad, S.M., Sajjadi, S.A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25-01-2008; Elsevier
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Elasticity, elastic constants; Elasticity. Plasticity; Exact sciences and technology; Martensitic transformations; Materials science; Mechanical and acoustical properties of condensed matter; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Mechanical properties of solids; Metals. Metallurgy; Ni–Ti orthodontic archwire; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Phase transformation; Physics; Pre-strain; Shape memory; Phase transformation; Shape memory; Ni–Ti orthodontic archwire; Pre-strain; Scanning electron microscopy; Prestress; Phase transformations; Martensitic transformations; Ni-Ti orthodontic archwire; Shape memory effects; Optical microscopy; Orthodontic procedures; Shape memory alloy; Superelasticity; Transition elements; Titanium; Biocompatibility; Nickel; Phase stability; Microstructure; Application
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2007.03.067

One of the most important applications of shape memory alloy is in medicine, especially orthodontic archwires. In this category Ni–Ti orthodontic archwires is one of the oldest used materials. Biocompatibility, corrosion resistance, super elasticity, etc. are its outstanding properties. In spite of the importance of dependency of pre-strain on microstructure of Ni–Ti there are limited sources concentrated on the subject. For this reason the main purpose of the current study is determination of the effect of pre-strain on microstructure of Ni–Ti orthodontic archwires. In this regard, three-point bending was performed on the orthodontic archwire specimens to apply different amount of strain. The microstructures were compared with the un-strained wire using optical and scanning electron microscopes. The results showed that the stable phase depends strongly on the value of pre-strain. Increasing pre-strain causes to decrease martensite laths and leads the microstructure toward austenite phase.