Download - Case for New Meteorite Metallurgy
The Case for aNew Metallurgy for Meteorites
Phyllis Z. BudkaTechnical Communications Unlimited
e-mail: [email protected]
Phyllis Z. Budka September 1, 2005 2
For nearly 200 years,the meteoritic Widmanstätten Structure
has been used to:
• Understand the fundamentals of irons and steels1800s to 1930s
– Invar effect 1900s to Present– Martensite 1920s to 1930s
• Develop metallurgical tools and techniques– Metallograph - 1850s– X-ray 1920s to 1930s– Microprobe - 1950s
• Develop the Fe-Ni phase diagram - 1904 to Present
• Calculate “Metallographic Cooling Rates” - Serve as the“thermometer” (geo-speedometer) for the study of small planetarybodies and asteroids - 1960s - Present
1813
Assumptions made long ago about nickel-iron meteorite formation conditions must be re-evaluated in the light of modern metallurgical understanding.
Phyllis Z. Budka September 1, 2005 3
The 1904 Fe-Ni Phase Diagram
Osmond and Cartaud1904
Assumptions - 1904• The meteoritic Widmanstätten structure is an equilibrium structure formed on
slow cooling.• The meteoritic Widmanstätten structure is formed by a solid state phase
transformation below 800C.• Meteoritic irons are similar to terrestrial irons except that meteoritic irons are
in equilibrium, whereas terrestrial irons are metastable.
KamaciteBody-centered cubic iron
Alpha ferrite
TaeniteFace-centered cubic iron
Gamma (Austenite)
Meteoritic Widmanstätten StructureTombouctou 25 diameters
Phyllis Z. Budka September 1, 2005 4
1948 Metals Handbook Fe-Ni Phase Diagram includes region above 1300 oC
Body Centered CubicDelta Ferrite
Body-centered cubic Delta Ferrite:• A primary crystallization structure formed above ~1500 oC.• Can be retained at room temperature.• Cannot be distinguished metallographically from body-centered cubic alpha iron.
Kamacite can also be interpreted as Delta Ferrite, formed by solidification from a melt.
Phyllis Z. Budka September 1, 2005 5
Today - Fe-Ni Phase Diagrams:Metallurgy vs Earth & Planetary Sciences
1987 McSween
1992 ASM Handbook 1992
Meteoritics
Metallurgy
Body Centered CubicDelta Ferrite
Face-centered cubic Austenite
Body Centered Cubic Alpha Ferrite
Phyllis Z. Budka September 1, 2005 6
Metallurgical EquilibriumBinary Phase Diagram Determination Today
Today, equilibrium metallurgical binary phase diagrams aredetermined in carefully controlled laboratory experiments.
Nickel-iron meteorites are “metallurgical garbage cans,” containingelements such as carbon, sulfur, phosphorus, etc. that impact phaseformation.
Nickel-iron meteorites are completely inappropriate for metallurgical phase diagram determination.
Phyllis Z. Budka September 1, 2005 7
Assumptions about meteoritic Widmanstätten Structure made in 1904 remain unchanged today in the Earth & Planetary Sciences.
Kamacite
Taenite
1987 McSweenAssumptions• The meteoritic Widmanstätten structure is
an equilibrium structure formed on slowcooling.
• The meteoritic Widmanstätten structure isformed by a solid state phasetransformation below 800C.
• Meteoritic irons are similar to terrestrialirons except that meteoritic irons are inequilibrium, whereas terrestrial irons aremetastable.
Assumptions• The meteoritic Widmanstätten structure is
an equilibrium structure formed on slowcooling.
• The meteoritic Widmanstätten structure isformed by a solid state phasetransformation below 800C.800C. 910C
• Meteoritic irons are similar to terrestrialirons except that meteoritic irons are inequilibrium, whereas terrestrial irons aremetastable.
Osm
ond
& C
arta
ud19
04After Owen & Liu1949 ++++
Kamacite is not necessarily an equilibrium structure.
Phyllis Z. Budka September 1, 2005 8
Definition of Widmanstätten Structure:Change in meaning from Morphology to Mechanism over Time
1985 ASM Metals Handbook
Widmanstätten structure. A structure characterized by a geometrical patternresulting from the formation of a new phase along certain crystallographicplanes of the parent solid solution. The orientation of the lattice in the newphase is related crystallographically to the orientation of the lattice in theparent phase. This structure was originally observed in meteorites, but isreadily produced in many other alloys, such as titanium by appropriate heattreatment.
1948 ASM Metals Handbook
Between 6 and 25% Ni, the alloys are martensitic after fast cooling; afterslow cooling or reheating, they decompose into alpha + gamma. Thestructure varies from the martensitic to the Widmanstätten typeobserved in meteorites.
Phyllis Z. Budka September 1, 2005 9
Widmanstätten Structure: 1813 - TodayA change in meaning over time: From Morphology to Mechanism
Cast single crystal nickel superalloy
Morphology does not imply mechanism.
Specimen courtesy of Dr. V. Buchwald
Agpalilik Nickel-Iron
Vacuum deposited nickel superalloy
Phyllis Z. Budka September 1, 2005 10
Meteoritic Widmanstätten StructuresCourtesy Dr. C.B. Moore
Equilibrium Assumption Microstructures are considered to be unchanged from theirstructure inside the meteorite parent body, except for a 10 mm heat-affected zone.
Implication: In the transition from inside the meteorite parent body to Earth arrival, these materials never reached their melting point.
The melting point of pure iron is 1538 oC.
Phyllis Z. Budka September 1, 2005 11
Metallographic Cooling Rate Theory and the“Widmanstätten Mechanism”
After Wood 1967Co
FCC
FCC
BCC
FCC
BCC
Phyllis Z. Budka September 1, 2005 12
FCC
BCC
340
Assumed equilibrium compositionof FCC taenite inside the
meteorite parent body.
After Wood 1967
Phyllis Z. Budka September 1, 2005 13
Metallographic Cooling Rates are derived from theslope of this line
BCC BCC
BCC BCC
through a mathematicalmodel based on theassumption that this point isthe equilibrium compositionof taenite/”austenite” insidethe meteorite parent body.
Typical Meteoritic Widmanstätten Structure
Typical microprobe trace
FCC
After Mc Sween 1987
Phyllis Z. Budka September 1, 2005 14
FCC
BCC
340
Metallographic Cooling Rates
• 1985 Narayan and Goldstein: Major revision of iron meteorite coolingrates:150 to 6000C per million years.
• 1987 McSween: “Cooling rate data foriron meteorites favor the last 3 models,unless parent bodies with central coreswere very small.”
McSween 1987
Meteorite Parent Body Models
Phyllis Z. Budka September 1, 2005 15
Metallographic Cooling Rate Theory
This is circular reasoning!
The Metallographic Cooling Rate theory is founded on the 1904 assumptionthat kamacite (alpha ferrite) is formed from taenite (austenite) in a solid statephase transformation.
Phyllis Z. Budka September 1, 2005 16
Potential Factors Influencing the Macro/MicrostructuralDevelopment of the Meteoritic Widmanstätten Structure
• Solidification• Microgravity / Low Gravity / Free Fall• Undercooling
• Thermal and Compositional Gradients• Local Equilibrium
• Solid State Phase Transformations• Other??
It is time for a New Metallurgy for Meteorites!
Phyllis Z. Budka September 1, 2005 17
Year Author
1982 P.Z. Budka
1984 P.Z. Budka
1984 P.Z. Budka, F.F. Milillo
1984 P.Z. Budka
1986 P.Z. Budka, F.F. Milillo
1986 P.Z. Budka, F.F. Milillo
1986 P.Z. Budka, F.F. Milillo
1988 P.Z. Budka1993 P.Z. Budka & J.R.M. Viertl
1993 P.Z. Budka, J.R.M. Viertl, S.V. Thamboo
1995 P.Z. Budka, J.R.M. Viertl, S.V. Thamboo
1996 P.Z. Budka, J.R.M. Viertl, S.V. Thamboo
1996 P.Z. Budka1996 P.Z. Budka
1997 P.Z. Budka, J.R.M. Viertl, S.V. Thamboo, R.E. LaRose
1998 P.Z. Budka and J.R.M. Viertl
1998 P.Z. Budka, J.R.M. Viertl T. B Schumaker
2001 P.Z. Budka and J.R.M. Viertl
2002 P.Z. Budka
2003 P.Z. Budka
2003 P.Z. Budka
2004 P.Z. Budka
TitleThe Formation of Pallasitic Chondrules: Evidence for Rapid Solidification Under Microgravity ConditionsThe Influence of Gravitational Body Force in Meteoritic Chondrule and Lunar Glass FormationSpeculations on the Formation of Metallic Meteorite PhasesThe Formation of Chondrule-Containing Extraterrestrial Materials: Evidence for Rapid Solidification Under Microgravity CondditionsThe Inverse Peritectic Phase Transformation in the Fe-S System: Evidence for the Remelting of Troilite During CoolingSome Common Microstructural Features of Nickel-Iron Meteorites and Cast Ferrous AlloysImportance of Meteoritic Materials in Assessing the Influence of Microgravity on SolidificationMeteorites as Specimens for Microgravity ResearchMundrabilla: A Microgravity Casting
Meteorites and Microgravity Research
Gravity Independent Macro/Micro-structural Features: Lessons from Nickel-Iron Meteorites
Microgravity Solidification Microstructures as Illustrated by Nickel-Iron and Stony-Iron MeteoritesMeteorites and the Iron-Nickel Phase DiagramThe Evolution of Meteoritics and MetallurgyMundrabilla's Anomalous Macrostructural Features Revealed as Microgravity Cast Structures Based on Classical Solidification PrinciplesMetallography, Meteorites and the Fe-Ni Phase Diagram
Metallography, Meteorites and the Fe-Ni Phase Diagram
Industrial X-Ray Technique Applied to Mundrabilla
Stony-Iron Meteorites (Pallasites) - A Study of Nature's Microgravity Specimens
Reconstructing Meteorite Microstructures
Stepping Back in Time: Digital Reconstruction of the Imilac Pallasite Formation, Stepping Back in Time #2, Digital Reconstruction of the Gibeon Widmanstätten Structure,
Journal Vol., Pages
Meteoritics: The Journal of the Meteoritical Society Vol. 17, No. 4
Meteoritics: The Journal of the Meteoritical Society Vol. 19, No. 4, p. 201
Meteoritics: The Journal of the Meteoritical Society Vol. 19, No. 4, pp. 201 - 202
Journal of Non-Crystalline Solids pp. 413 - 419
Meteoritics: The Journal of the Meteoritical Society Vol. 24, No. 4, p.342
Meteoritics: The Journal of the Meteoritical Society Vol. 24, No. 4, pp. 342 - 343
Metallurgical Transactions A Vol. 19A, August 1988 pp. 1919 - 1923Meteoritics Vol. 28, No. 3, p. 333
Advanced Materials & Processes Vol. 144, No. 5, Nov. 1993, p. 4
7th International Symposium on Experimental Methods for Microgravity Materials Science, The Mineral, Metals & Materials Society
pp. 27 - 36
8th International Symposium on Experimental Methods for Microgravity Materials Science, The Mineral, Metals & Materials Society
pp. 49 - 57
Advanced Materials & Processes Vol. 150 No. 1, July 1996, pp. 27 - 30Meteorite! Vol. 2 No. 3, pp. 22 - 23
28th Lunar and Planetary Science Conference
28th Lunar and Planetary Science Conference Feb. 1998, pp. 22 - 23
61st Meteoritical Society Meeting
64th Meteoritical Society Meeting
14th International Symposium on Experimental Methods for Microgravity Materials Science
Advanced Materials & ProcessesVol. 161 No. 5, May 2003, www.asminternational.org/AMP, "Web Exclusives"
Meteorite Nov. 2003 Vol. 9, No. 4, pp. 21 - 22
Meteorite Nov. 2004 Vol. 10, No. 4, pp. 21 - 22
Budka Publications on Meteorite Metallurgy