Effect of Pressure on the Melting
Behavior of the Fe-S System at
Moderate Pressures
Bin Chen1, Jie Li1, Lili Gao1, Kurt
Leinenweber2, Yanbin Wang3, Takeshi
Sanehira3
1.
2.
3.
University of Illinois at Urbana-Champaign
Arizona State University
GSECARS
GSECARS, Advanced Photon Source
Source, Argonne National Laboratory
Outline
Á
Introduction
I t d ti
À
À
Á
Experimental Methods
À
Á
In situ x-ray radiographic technique
Results & Discussion
À
À
Á
Fe-S system and planetary cores
Pressure effect on liquidus curve
In situ observation of melting
Fe-S eutectic
Summaryy
Introduction
Motivation
The study of melting behaviour of Fe-S system at
high pressures allows us:
(1) to investigate solidification history of iron-rich
cores.
cores
((2)) to establish a link between sulfur content and
state of iron-rich cores.
(3) to
t understand
d t d the
th generation
ti off magnetic
ti field
fi ld
and convection in iron-rich liquid cores.
Introduction
Liquidus Curve
Positive departure from ideal solution at 1 bar
solution at 1 bar
Ideal or non‐ideal ?
10 GPa ?
14 GPa ?
3 GPa
1 bar
(Fei et al., 1997)
(Brett and Bell, 1969)
Introduction
Liquidus curves at 10 and 14 GPa
(Chen et al. submitted)
Introduction
Application to Mercury
Á
Á
Á
Á
CMB pressure is ~ 5
5-10
10 GPa,
GPa
Center pressure is ~40 GPa
W k magnetic
Weak
ti field
fi ld
Mercury’s core is at least
partially molten (Margot et al.
2007).
MESSENGER (MErcury (MErcury
Surface, Space ENvironment, GEochemistry, and Ranging) (From: http://sse.jpl.nasa.gov)
(From: http://sse.jpl.nasa.gov)
Introduction
Liquidus T in Mercury’s
Mercury s core
(Chen et al. submitted)
Introduction
Mercury
Mercury’ss Snowing Core
Bulk sulfur content > 7 wt %
Bulk sulfur content < 7 wt %
(Chen et al. submitted)
Introduction
Limited Data Coverage
Chen et al.
S b i d
Submitted
Y. Fei
Personal
Communication
?
?
Stewart et al.
2007
(Chen et al. submitted)
Experimental Methods
In situ Multi Anvil Experiments
In situ Multi Anvil Experiments
Á
Experimental setup
À
À
10/5 (by Kurt Leinenweber)
Double/single sample chamber
Graphite X-ray window in Re
heater
Run T0998 @
@1 bar
Fe-S (9 wt% S)
BN
Fe-S (4 wt% S)
~200 micron
X-ray radiographic image
GSECARS (13‐IDD)
Results & Discussion
In-situ
In situ Observation of Melting (1)
1 bar
P=14 GPa
9 wt% S
(Fe-S)
Run T0898
T (°C)
25
733
838
857
883
Eutectic Melting
9 wt.% S
(Fe-S)
BN
4 wt.%
t%S
(Fe-S)
T ((°C)
C)
915
1006
1200
1300
1364
1400
Totally Molten
~200 micron
GSECARS (13‐IDD)
Eutectic T=860 °C @ 14 GPa
(Fei et al. 1997)
Introduction
Consistent with Quench Experiments
9 wt%
t% S
(Chen et al. Submitted)
Results & Discussion
In-situ
In situ Observation of Melting (2)
1 bar
P= 13.4 GPa
Fe-S
((9 wt% S))
Fe-S
Fe
S
(4 wt% S)
800
832
859
893
T ((°C)
C)
Eutectic Melting
Run T0899
930
GSECARS (13‐IDD)
963
1059
1300
T ((°C))
Totally Molten
Results & Discussion
In-situ
In situ Observation of Melting (3)
1 bar
P= 16 GPa
Fe-S
(9 wt% S)
300
870
880
900
T ((°C)
C)
1450
Eutectic Melting
~470 micron
@1350 °C
Run T0901
GSECARS (13‐IDD)
<1
2
5
10
Time (min)
15
Results & Discussion
Fe-S
Fe S Eutectic
Fe3S
Fe3S2
Results & Discussion
In situ X-ray
X ray radiography
Á
Advantage
À
In situ p
pressure measurement
¿
Same Load 400 tons
¾
¾
¾
¿
À
T0898 ((double sample
p chamber):
) 14 GPa
T0899 (double sample chamber): 13.4 GPa
T0901 (single sample chamber): 16 GPa
Pressure at high temperature
High efficiency
¿
¿
Determine eutectic melting temperature (possibly
eutectic composition) in one run
M
Multiple
lti l points
i t on th
the liliquidus
id curve iin one run
Summary
Á
Á
In
I situ
it X-ray
X
radiographic
di
hi technique
t h i
in
i multi-anvil
lti
il
apparatus is a promising technique to
investigation of melting at high pressure.
pressure
Advantages
À
Hi h accuracy
High
¿
À
In situ pressure measurement
High efficiency
¿
¿
Determine the eutectic temperature in one run
Multiple
p p
points on liquidus
q
curve in one run
Acknowledgements
Á
Á
Á
Á
Á
Á
Á
Á
Á
Y. Fei, C. Hadidiacos, D. George
D. Payne,
y
F. Huang
g
N. Chabot
David Walker
Liz Cottrell
Andrew Campbell
Dane Morgan
Henry P. Scott
Craig Bethke
Thank You!