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Interaction between refractory crucible materials and the melted NiTi shape-memory alloy

Sadrnezhad, S. K ; Sharif University of Technology | 2005

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  1. Type of Document: Article
  2. DOI: 10.1007/s11663-005-0068-2
  3. Publisher: Minerals, Metals and Materials Society , 2005
  4. Abstract:
  5. Attempts have been made to quantify the amount of contaminants absorbed by liquid metal from commercial ZrO2-, Al2O3-, and SiC-base crucibles used for vacuum melting of Ni-45 wt pet Ti alloy. The molten alloy was held under vacuum for 90 minutes at 1450°C to become homogenized. Reactions between the liquid metal and the crucible were investigated by visual observation, chemical analysis, scanning electron microscopy (SEM) image processing, and X-ray mapping. The relative degree of contamination declined in the following sequence: commercially pure SiC > SiC-5 wt pct Al2O3-5 wt pet SiO2] > slurry cast alumina > recrystallized alumina > zircon type A > oxygen deficient high-purity zirconia. Thermodynamic calculations showed a difference between the equilibrium and the experimental data, indicating that except for commercially pure SiC crucible, the amount of the crucible elements entering the melt is greater than the calculated equilibrium values. This discrepancy seems to be due to the immersion into the melt of the undissolved chemical compounds formed due to the reactions between the crucible and the liquid phase
  6. Keywords:
  7. Composition ; Dissolution ; Impurities ; Liquid metals ; Phase equilibria ; Scanning electron microscopy ; Shape memory effect ; Thermal effects ; X ray analysis ; Zirconia ; Liquid phase ; Melted NiTi shape-memory alloys ; Particle-induced X-ray spectroscopy (PIXRS) ; X-ray mapping ; Refractory materials
  8. Source: Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science ; Volume 36, Issue 3 , 2005 , Pages 395-403 ; 10735615 (ISSN)
  9. URL: https://link.springer.com/article/10.1007/s11663-005-0068-2