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Properties of Small Metallic Particles

Properties of Small Metallic Particles. Helen Chappell Aikaterina Plati Yi Shen. Carbon nanotube with iron particle in the middle. blobby iron particle. Kinloch, 2002. What we did…. Iron particles 10-wt% nickel-iron alloy particles Varied shape, size and composition

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Properties of Small Metallic Particles

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  1. Properties of Small Metallic Particles Helen Chappell Aikaterina Plati Yi Shen

  2. Carbon nanotube with iron particle in the middle blobby iron particle Kinloch, 2002

  3. What we did… • Iron particles • 10-wt% nickel-iron alloy particles • Varied shape, size and composition • Statistical sampling of ‘homogeneous’ alloy

  4. Melting Temperature • Flat interface, GL = GS

  5. Melting Temperature solid free energy liquid Tm temperature

  6. Melting Temperature • Flat interface, GL = GS Curved interface, GL = GS + s ds/dn

  7. s (ds/dn) Tmr Melting Temperature solid free energy liquid Tm temperature

  8. Created Curvefit3 Process • Mt data (GL , Gs ) Fitted polynomial equations to the data GL=AT2 + BT + C Gs=DT2 + FT + L GSR= GS + s ds/dn Gsr,Tm(r)|x,s Plotted results in Excel

  9. 1811.5 K 391.8K Melting temperature for spherical ferrite particles 2000 s=0 J/m2 1600 s=0.1J/m2 1200 s=0.5J/m2 Temperature /K 800 s=1J/m2 400 0 0 2108 4108 6108 8108 10108 12108 1/Radius /m-1

  10. 1661.5 K 112.8K Melting temperature for spherical austenite particles 2000 s=0 s=0J/m2 s=0 s=0.1 1600 s=0.1J/m2 s=0.1 1200 s=0.5 s=1 Temperature /K 800 400 s=1 s=1J/m2 0 0 2108 4108 6108 8108 10108 12108 1/Radius /m-1

  11. 1661.5 K Melting temperature for cylindrical austenite particles 2000 s=0J/m2 s=0 s=0.1J/m2 s=0 s=0.1 1600 s=0.1 1200 s=1J/m2 s=0.5 s=1 Temperature /K 844.4K 800 400 s=1 0 0 2108 4108 6108 8108 10108 12108 1/Radius /m-1

  12. Nickel-iron particles • Gs-ferrite y = -0.0172T2 – 35.564T + 7602.5 • Gs-austenite y = -0.0141T2 – 44.14T + 12886 • GL y = -0.0146T2 – 50.209T + 25307

  13. Melting temperature for cylindrical austenite particles in alloy (10%Ni) Tm=1784.3K 2000 s=0 s=0 s=0.1 1600 s=0.1 1200 s=0.5 s=1 Temperature /K 800 400 s=1 0 0 2108 4108 6108 8108 10108 12108 1/Radius /m-1

  14. Melting temperature for spherical ferrite particles in alloy(10% Ni) Tm=1754.84 1600 1200 Temperature /K 800 400 2108 4108 6108 8108 10108 0 (1/Radius) /m-1

  15. Melting temperature of austenite and ferrite particles in pure iron and alloy(10%Ni)s=0.5 1800 1600 Temperature /K 1200 800 400 2108 4108 6108 8108 10108 0 (1/Radius) /m-1

  16. Statistical Analysis • Fixed volume • Np  Na= constant • sx= Na f(1-f) , f=0.1 • Na = (4/3 p r3)/Vm N

  17. s = 0.1Jm-2 s = 0.2 Jm-2 s = 0.3 Jm-2 s = 0.4 Jm-2 s = 0.5 Jm-2 2108 4108 6108 8108 10108 Statistically derived melting temperature for Fe - Ni particles 2000 1600 1200 Temperature /K 800 400 0 0 1/Radius /m-1

  18. Summary of Results • Spherical particles reduce Tmr by greatest amount • Cylindrical particles reduce Tmr • Small particles, large s - reduces Tmr • Iron - austenite largest reduction in Tmr • Alloy - ferrite largest reduction in Tmr • Extremely small particles - composition influences melting temperature

  19. That’s all folks!

  20. The change in ds/dn • Sphere = 2Vm/ r • Cylinder = Vm/r

  21. MT-DATA • Thermodynamic data – SGTE database • Minimises Gibbs free energy - Equilibrium Composition - Volume fractions of phases • Phases can be suppressed • No kinetic information

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