title: Micro-XRD study of beta-titanium wires and infrared soldered joints.
abstract: OBJECTIVE
  The purpose of this study was to investigate the metallurgical phases in beta-titanium soldered joints prepared by infrared soldering, using the Micro X-ray diffraction technique (Micro-XRD), and to characterize the Vickers hardness in the soldered beta-titanium wires.
  
  
  METHODS
  Beta-titanium wires with cross-section dimensions of 0.032in.x0.032in. (TMA, Ormco), and both titanium-based solder (Ti-30Ni-20Cu, Selec) and silver-based solder (Ag-22Cu-17Zn-5Sn, Tomy) were selected. Soldering was performed using infrared radiation (RS-1, Morita) under argon atmosphere. Micro-XRD analyses were performed at room temperature. Micro-XRD spectra were obtained for the boundary region of the soldered beta-titanium wires using 50microm and 10microm diameter analysis regions. Hardness was measured at 30microm intervals from boundary of the diffusion layer and beta-titanium wire. The Kruskal-Wallis test with the Bonferroni and Wilcoxson Mann-Whitney tests for nonparametric means were employed as statistical methods (P<0.05).
  
  
  RESULTS
  For both types of soldered beta-titanium samples, the Micro-XRD spectra contained four major peaks for body-centered cubic (bcc) beta-titanium. Additional peaks at about 41 and 45 degrees are attributed to Cu-Ti intermetallic phase(s), which may be metastable under soldering conditions. The diffusion layer had greater hardness than bulk beta-titanium for both types of soldered specimens (P<0.05).
  
  
  CONCLUSIONS
  Soldering of beta-titanium orthodontic wire by infrared radiation may be acceptable for clinical use, since Micro-XRD spectra revealed that both types of soldered specimens largely retained the bcc beta-titanium structure. Further research is needed to investigate the mechanical properties and corrosion behavior of infrared-soldered beta-titanium wire.
authors.affiliation: Department of Orthodontics, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293, Japan. iijima@hoku-iryo-u.ac.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Iijima
authors.forename: William A
authors.initials: WA
authors.lastname: Brantley
authors.forename: Naoki
authors.initials: N
authors.lastname: Baba
authors.forename: Satish B
authors.initials: SB
authors.lastname: Alapati
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Yuasa
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ohno
authors.forename: Itaru
authors.initials: I
authors.lastname: Mizoguchi
mesh_terms: D000497:Alloys / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D012994:Dental Soldering; D004058:Diffusion; D004577:Electron Probe Microanalysis; D006244:Hardness; D006801:Humans; D007259:Infrared Rays; D008422:Materials Testing; D019563:Mechanics; D008669:Metallurgy; D015591:Microspectrophotometry; D009532:Nickel / Q000737:chemistry; D009969:Orthodontic Wires; D012834:Silver / Q000737:chemistry; D013499:Surface Properties; D014001:Tin / Q000737:chemistry; D014025:Titanium / Q000032:analysis / Q000737:chemistry*; D014961:X-Ray Diffraction; D015032:Zinc / Q000737:chemistry
chemical_list: D000497:Alloys; D012834:Silver; D014001:Tin; D003300:Copper; D009532:Nickel; D014025:Titanium; D015032:Zinc