CHapter 7- SYstems with 2 components

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CHapter 7- SYstems with  2 components Powered By Docstoc
					Ternary Systems

 Readings:
 Winter Chapter 7
           C = 3: Ternary Systems:
           Example 1: Ternary Eutectic
                          Di - An - Fo
                                             Anorthite
Note three binary eutectics
No solid solution
Ternary eutectic = M




                                         M

                                                                T



                                                         Forsterite
                              Diopside
T - X Projection of Di - An - Fo

                           Isobaric diagram
                           illustrating the
                           liquidus temperatures
                           in the Di-An-Fo
                           system at
                           atmospheric pressure
                           (0.1 MPa). After
                           Bowen (1915), A. J.
                           Sci., and Morse
                           (1994), Basalts and
                           Phase Diagrams.
                           Krieger Publishers.
Crystallization Relationships
            Liquid      a
                                       An
                            An + Liq
 Di + Liq

              Di + An




 Pure Fo forms
Just as in binary
      f=?
      F=?
   f   = 2 (Fo + Liq)
    F = 3 - 2 + 1 = 2

If on liquidus, need to specify
   only 2 intensive variables
  to determine the system
             liq
    T and X An or
        liq      liq
    X An and X Fo


   X of pure Fo is fixed
Lever principle  relative proportions of liquid & Fo
          o
 At 1500 C

        Liq  x + Fo = bulk a
   x/Fo = a-Fo/x-a
New continuous reaction as liquid follows cotectic:
    LiqA  LiqB + Fo + Di
Bulk solid extract
Di/Fo in bulk solid extract using lever principle

                                   1274          M



                                      b


                                                     Fo + Liq
                     1392
                    Diopside   c          1387
 At1300oC liquid = X
 Imagine triangular plane X - Di - Fo balanced on bulk a

     Liq x

                a
Di
                    m          Fo


     /              /
Liq total solids = a-m Liq-a

 total Di/Fo = m-Fo/Di-m
Partial Melting (remove melt):
                 Fo - An - SiO2   (at 0.1 MPa)

  3 binary systems:
      Fo-An eutectic
      An-SiO2 eutectic
      Fo-SiO2 peritectic


Isobaric diagram
illustrating the cotectic
and peritectic curves in
the system forsterite-
anorthite-silica at 0.1
MPa. After Anderson
(1915) A. J. Sci., and
Irvine (1975) CIW
Yearb. 74.
                         x
                     b
             a




Fo   1890   En   y
Works the same way as the Fo - En - SiO2 binary




                               i
                      k
               1557




          Fo              En
              f

          e   b




Fo   En
              Diopside-Albite-Anorthite
Isobaric diagram
illustrating the liquidus
temperatures in the
system diopside-
anorthite-albite at
atmospheric pressure
(0.1 MPa). After Morse
(1994), Basalts and
Phase Diagrams.
Krieger Publushers

Di - An Eutectic
Di - Ab Eutectic
Ab - An solid solution
              Isobaric diagram
              illustrating the liquidus
  Isobaric    temperatures in the
              system diopside-
polythermal   anorthite-albite at
              atmospheric pressure
 projection   (0.1 MPa). After Morse
              (1994), Basalts and
              Phase Diagrams.
              Krieger Publishers.
Binary character is usually maintained
when a new component is added

 Eutectic behavior remains eutectic
 Peritectic behavior remains peritectic
 Solid solutions remain so as well

				
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posted:2/16/2012
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