Magnetic Susceptibility Studies of the Influences of Thermomechanical Processing and Mn Addition on Phase Stability and Precipitation in NbTi Alloys

  • D. S. Pyun
  • R. D. Smith
  • E. W. Collings
Part of the An International Cryogenic Materials Conference Publication book series (ACRE, volume 40)


The DC magnetic susceptibilities, χ, of series of NbTi and NbTiMn(0.5 at. %) alloys were measured using the Faraday (Curie) balance technique over the temperature range 77–300 K. The samples were measured in the conditions: (i) β-quenched (β-Q), (ii) cold worked (CW), and (iii) CW plus precipitation-heat-treated (CW+PHT). It was found that: (1) For the β-Q samples dχ/dT, which was positive within 77–300 K, increased as the Nb concentration decreased — effects that are attributable to the influences of temperature and Nb concentration, [Nb], on reversible ω-phase formation. (2) By the same token, due to its β-stabilizing effect, the addition of 0.5% Mn increased χ at 77 K. (3) The susceptibility results also showed evidence for the removal of ω phase by cold work. (4) As a result of α-phase precipitation, heat treatment substantially reduced the x of the CW+PHT samples below those of both the β-Q- and CW alloys. The [Nb] dependence of α-phase abundance, f α , was deduced from the χ data at RT where the ω-phase contribution was negligible; by comparing the [Nb] dependence of f α for the NbTi and NbTiMn alloys the β-stabilizing potency of Mn was estimated. Finally, the absence of any measurable Curie-Weiss component in the χα-phase(T) of a NbTiMn(0.5 at. %) alloy after CW+PHT indicated that the Mn content of the α-phase precipitate was negligibly small, i.e. less than about 250 ppm.


Magnetic Susceptibility Cold Work Composition Dependence Niobium Concentration Molar Susceptibility 
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Copyright information

© Springer Science+Business Media New York 1994

Authors and Affiliations

  • D. S. Pyun
    • 1
  • R. D. Smith
    • 1
  • E. W. Collings
    • 1
  1. 1.Battelle Memorial InstituteColumbusUSA

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