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Subroutine MAP_STEEL_CRITRAD

  1. Provenance of code.
  2. Purpose of code.
  3. Specification.
  4. Description of subroutine's operation.
  5. References.
  6. Parameter descriptions.
  7. Error indicators.
  8. Accuracy estimate.
  9. Any additional information.
 10. Example of code
 11. Auxiliary subroutines required.
 12. Keywords.
 13. Download source code.
 14. Links.

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Provenance of Source Code

J.D. Robson,
Phase Transformations Group,
Department of Materials Science and Metallurgy,
University of Cambridge,
Cambridge, U.K.

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Purpose

To calculate the critical (minimum) radius of needles growing under
diffusion control.

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Specification

SUBROUTINE MAP_STEEL_CRITRAD(RC, AV, SE, XA, XC, XB, TK, K)

DOUBLE PRECISION RC, AV, SE, XA, XC, XB, TK, K

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Description

Calculates the minimum radius possible from capillarity considerations for
needle shaped precipitate growth.

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References

1. J.W. Christian, Transformations in Metals and Alloys, Pergamon Press,
(1975), 181, 439.

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Parameters

Input parameters

AV - real
     AV is the atomic volume (in metres cubed, m3).

SE - real
     SE is the interfacial energy (in joules per metre squared, Jm-2).

XA - real
     XA is the concentration in the matrix at the needle tip.

XC - real
     XC is the concentration in the precipitate.

XB - real
     XB is the concentration in the matrix far from the needle.

TK - real
     TK is the thermodynamic temperature (in kelvin, K).

K - real
     K is the Boltzmann constant (in joules per kelvin, JK-1).

Output parameters

RC - real
     RC is the critical radius for needle growth.

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Error Indicators

None.

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Accuracy

No information supplied.

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Further Comments

None.

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Example

1. Program text

       DOUBLE PRECISION RC, AV, SE, XA, XC, XB, K
       INCLUDE 'map_constants_boltz.f'
       READ (5,*) AV, SE, XA, XC, XB, TK
       CALL MAP_STEEL_CRITRAD(RC, AV, SE, XA, XC, XB, TK, K)
       WRITE (6,10) RC
10     FORMAT ('RC=', E13.5)
       STOP
       END

2. Program data

1.868E-29   0.6   0.005   0.5   0.01   873

3. Program results

RC = 3.73830E-09

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Auxiliary Routines

None.

Keywords

needle precipitate, critical radius

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The MAP Project originated from a joint project of the National Physical
Laboratory and the University of Cambridge.

Contact Information :-

Harry Bhadeshia / hkdb@cus.cam.ac.uk
Hugh Davies / rhd@newton.npl.co.uk
Web site admin. / map@cam.ac.uk

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