“Mulberry (uranium alloy)”的意思、由来-开放百科全书

It is used as a non-corroding^[1] or 'stainless'^[2] uranium alloy. It has been put forward as a structural material for the casings of the physics package in nuclear weapons, including those of North Korea.{{sfn|Jane's, North Korea|page=9 }}

The composition is a ternary alloy,^[4]^[5] of 7.5% niobium, 2.5% zirconium, 90% uranium.

Mulberry was developed in the 1960s at UCRL.^[5]^[8] Binary alloy compositions were first studied to avoid the mechanical problems of pure uranium: corrosion, dimensional instability, inability to improve its mechanical properties by heat treatment.^[9] Uranium-molybdenum alloys were found susceptible to stress-corrosion cracking, uranium-niobium alloys to be weak, and uranium-zirconium alloys to be brittle.^[9] Ternary alloys were next studied to try to avoid these drawbacks. Uranium-niobium-zirconium was found to be corrosion resistant and to permit age hardening, which could increase its hardness from 110 to 270 ksi.^[9]^[12]

Multiple crystal phases were observed, with a critical temperature of 650°C. Above this the body-centered cubic γ phase was stable. Water quenching to room temperature produces a γ^s transition phase and with aging this transforms to a tetragonal γ^o phase. Further aging produces a monoclinic ɑ{{}} phase that is observed metallographically as a Widmanstätten pattern.^[13]^[14] The crystal structure of the alloy has been studied, particularly the γ phase.^[5]^[8]^[17]^[18] Uranium inclusions have been observed within the alloy although, unlike the binary alloys, niobium-rich inclusions were not.^[19] Early studies were uncertain as to whether these were inherent behaviours, or artifacts of their processing.

References

1. ^¹²³{{Cite paper|title=Mechanical Properties of Some Uranium Alloys|last1=Vandervoort |first=R.R.|last2= Peterson |first2=C.A.W.|id=UCRL-7771|publisher=UCRL|year=1964|url=https://digital.library.unt.edu/ark:/67531/metadc1031428/}}
2. ^¹²{{Cite paper|last1=Vandervoort |first=R.R.|last2= Peterson |first2=C.A.W.|title=The Properties of a Metastable Gamma Phase Uranium-base Alloy: U-7.5 Nb 2.5 Zr|publisher=UCRL|id=UCRL-7869|year=1964|url=https://digital.library.unt.edu/ark:/67531/metadc867893/}}
3. ^¹{{Cite paper|title=Plutonium and Uranium as Engineering Materials|id=AEC Contract No. W-7405-eng-48|first=Charles R. |last=Henry|date=February 26, 1965|publisher=UCRL|url=https://www.osti.gov/scitech/servlets/purl/4546042|pages=7–8}}
4. ^¹{{Cite journal|volume=82 |issue=1|date=June 1979|pages=184-192|journal=J. Nucl. Mater.|title=Stability of the body-centered cubic gamma phase in the uranium-zirconium-niobium system|first=R.O. |last=Williams|doi=10.1016/0022-3115(79)90052-7|bibcode=1979JNuM...82..184W}}
5. ^¹{{Cite journal|journal=J. Vac. Sci. Technol.|volume=8 |issue=1|page=80|doi=10.1116/1.1316361|year=1971|title=Oxidation of a Ternary Uranium Alloy|first=D.T. |last=Larson|bibcode=1971JVST....8...80L}}
6. ^¹²³{{Cite journal|title= Flow behavior of mulberry uranium|last=Hoge |first1=K.G|last2=Kuhn |first2=B.A.|last3=Reshenk |first3=V.L.|publisher=California Univ., Livermore (USA). Lawrence Livermore Lab|id=UCRL--51346|year=1973|volume=4 |issue=18|url=http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/04/075/4075681.pdf?r=1}}
7. ^¹{{Cite journal|title=Evaluation of Uranium Alloys|first1=W. C. |last=Erickson|first2=G. E. |last2=Jaynes|first3=D. J. |last3=Sandstrcsn|first4=R. |last4=Seegmiller|first5=J. M. |last5=Taub|date=September 1972|publisher=LASL|url=http://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-05002|pages=8–13}}
8. ^¹{{Cite paper|title=Recent Observations of Phase Transformations in a U-Nb-Zr Alloy|first1=R.A. |last=Vandermeer|year=1973|publisher=Metals and Ceramics Division, Oak Ridge National Laboratory|url=https://www.osti.gov/scitech/servlets/purl/4309129}}
9. ^¹{{Cite paper|title=A Study of the Time-Temperature Transformation Behavior of a Uranium=7.5 weight per cent Niobium-2.5 weight per cent Zirconium Alloy|first1=C.W. |last=Dean|date=24 October 1969|id=Oak Ridge Report Y-1694|publisher=Union Carbide Corporation, Y-12 Plant, Oak Ridge National Laboratory|url=https://digital.library.unt.edu/ark:/67531/metadc1033722/m2/1/high_res_d/4749751.pdf}}
10. ^¹{{Cite book|title=Electron Microscopy and Structure of Materials|editor=Gareth Thomas|editor2=Richard M. Fulrath|editor3=Robert M. Fisher|publisher=University of California Press|year=1972|isbn=0520021142|pages=340–345|url=https://books.google.co.uk/books?id=1yiRUg7ooO8C&pg=PA340&lpg=PA340}}
11. ^¹{{Cite journal|journal=J. Less Common Met.|volume=27 |issue=1|date=April 1972|pages=9-15|title=The elastic constants of uranium-7.5% niobium-2.5% zirconium as a function of pressure|first1=A.E. |last1=Abey|first2=E.D. |last2=Joslyn|doi=10.1016/0022-5088(72)90099-9}}
12. ^¹{{Cite journal|journal=Journal of Nuclear Materials|volume=449, Issues 1–3, June 2014, Pages 23-30|title=Gamma-phase homogenization and texture in U–7.5Nb–2.5Zr (Mulberry) alloy|first1=Denise Adorno |last1=Lopes|first2=Thomaz Augusto Guisard |last2=Restivo|first3=Nelson Batista |last3=de Lima|first4=Angelo Fernando |last4=Padilha|doi=10.1016/j.jnucmat.2014.02.030|bibcode=2014JNuM..449...23L}}
13. ^{{Cite book|title=Central Florida Phosphate Industry: Environmental Impact Statement|volume=2|publisher=United States. Environmental Protection Agency|year=1979|url=https://books.google.com/books?id=Q_g0AQAAMAAJ&pg=SA2-PA26|page=2}}