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)

Abstract

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.

Keywords

Titanium Manganese Encapsulation Cold Work Boulder 

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References

  1. 1.
    E. W. Collings, K. R. Marken, Jr., J. C. Ho, and T. S. Kreilick, Effect of manganese additions on the physical-and superconducting properties of Nb-46.5Tí, in “Cryogenic Materials ‘88, Vol.1: Superconductors”, R. P. Reed, Z. S. Xing, and E. W. Collings, eds., ICMC, Boulder, 1988, p. 343.Google Scholar
  2. 2.
    E. W. Collings, R. D. Smith, J. C. Ho, and C. Y. Wu, Low temperature specific heat and magnetic susceptibility of NbTi and NbTiMn alloys, Adv. Cryo. Eng. Materials 36, 239 (1990).CrossRefGoogle Scholar
  3. 3.
    D. S. Pyun and E. W. Collings, Metallurgical, physical, and superconducting properties of series of NbTi and NbTiMn alloys, Adv. Cryo. Eng. Materials 38, 667 (1992).Google Scholar
  4. 4.
    D.S. Pyun and E. W. Collings, Influence of manganese on the upper critical field of two series of,3-quenched-and precipitation-heat-treated NbTi alloys - paper in this proceedings.Google Scholar
  5. 5.
    E. W. Collings and R. D. Smith, The magnetic susceptibility of titanium-niobium alloys, J. Less-Common Metals 48, 187 (1976); see also E. W. Collings and R. D. Smith, The magnetic susceptibility of niobium, J. Less-Common Metals 27, 389 (1972).Google Scholar
  6. 6.
    E. W. Collings, “Applied Superconductivity, Metallurgy and Physics of Titanium Alloys”, Vols. 1 and 2, Plenum Press, N.Y. (1986).Google Scholar
  7. 7.
    Reference 6, Vol 1 pp. 297–303.Google Scholar
  8. 8.
    Reference 6, Vol.1, pp. 38–47.Google Scholar
  9. 9.
    E. W. Collings, “Physical Metallurgy of Titanium Alloys”, ASM, Materials Park, OH (1984), pp. 100–108.Google Scholar
  10. 10.
    Reference 1; see also Reference 6, Vol. 1 p. 293; see also J. A. Cape, Superconductivity and localized magnetic states in Ti-Mn alloys, Phys. Rev. 132 1486 (1963).Google Scholar
  11. 11.
    E. W. Collings and J. C. Ho, Magnetic susceptibility and low temperature specific heat of high-purity titanium, Phys. Rev. B 2, 235 (1970).Google Scholar

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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