Skip to main content
Article
Differential Scanning Calorimetry (DSC) Analyses of Superelastic and Nonsuperelastic Nickel-Titanium Orthodontic Wires
American Journal of Orthodontics and Dentofacial Orthopedics
  • T. Gerard Bradley, Marquette University
  • William A. Brantley, Ohio State University - College of Dentistry
  • Bill M. Culbertson, Ohio State University - College of Dentistry
Document Type
Article
Language
eng
Format of Original
9 p.
Publication Date
6-1-1996
Publisher
Elsevier
Disciplines
Abstract
The purpose of this study was to determine the transformation temperatures for the austenitic, martensitic, and rhombohedral (R) structure phases in representative as-received commercial nitinol (NiTi) orthodontic wire alloys, to reconcile discrepancies among recent publications. Specimens were examined by differential scanning calorimetry (DSC) over a temperature range from approximately −170° C to 100° C, with a scanning rate of 10° C per minute. Two different pathways, with the intermediate R structure either absent or present, were observed for the transformation from martensitic to austenitic NiTi, whereas the reverse transformation from austenitic to martensitic NiTi always included the R structure. The enthalpy (ΔH) for the transformation from martensite to austenite ranged from 0.3 to 35 calories per gram. The lowest ΔH value for the nonsuperelastic Nitinol wire is consistent with a largely work-hardened, stable, martensitic microstructure in this product. The DSC results indicate that the transformation processes are broadly similar in superelastic, body-temperature shape-memory, and nonsuperelastic NiTi wires. Differences in bending properties for the NiTi orthodontic wires at room temperature and 37° C are due to the relative proportions of the metallurgical phases in the microstructures.
Comments

American Journal of Orthodontics and Dentofacial Orthopedics, Vol. 109, No. 6 (June 1996): 589-597. DOI.

T. Gerard Bradley was affiliated with The Ohio State University at the time of publication.

Citation Information
T. Gerard Bradley, William A. Brantley and Bill M. Culbertson. "Differential Scanning Calorimetry (DSC) Analyses of Superelastic and Nonsuperelastic Nickel-Titanium Orthodontic Wires" American Journal of Orthodontics and Dentofacial Orthopedics (1996) ISSN: 1097-6752
Available at: http://works.bepress.com/t_bradley/15/