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homogeneous nucleation

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Published: 01 December 2008
Fig. 9 Comparison between heterogeneous nucleation (A) and homogeneous nucleation (B) in terms of the relative transformation kinetics below the melting point. The reduced temperature T r = T / T f and time t ∝ l −1 . T g , glass transition temperature More
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Published: 31 October 2011
Fig. 8 Comparison of free-energy changes associated with homogeneous nucleation, heterogeneous nucleation, and fusion welding More
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Published: 27 April 2016
Fig. 14 Free-energy curves for homogeneous nucleation. Source: Ref 2 More
Series: ASM Handbook
Volume: 1A
Publisher: ASM International
Published: 31 August 2017
DOI: 10.31399/asm.hb.v01a.a0006311
EISBN: 978-1-62708-179-5
... describes various undercooling methods, including kinetic undercooling, thermal undercooling, constitutional undercooling, and pressure undercooling. For solidification to occur, nuclei must form in the liquid. The article discusses the various types of nucleation: homogeneous nucleation, heterogeneous...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005207
EISBN: 978-1-62708-187-0
.... The article describes nucleation phenomenon such as homogeneous nucleation and heterogeneous nucleation. It examines various grain refinement models, such as the carbide-boride model, the free growth model, and the constitutional undercooling model. The article concludes with information on the thermal...
Series: ASM Handbook
Volume: 9
Publisher: ASM International
Published: 01 December 2004
DOI: 10.31399/asm.hb.v09.a0003731
EISBN: 978-1-62708-177-1
... Abstract Precipitation reactions occur in many different alloy systems when one phase transforms into a mixed-phase system as a result of cooling from high temperatures. This article discusses the homogenous and heterogeneous nucleation and growth of coherent and semicoherent precipitates...
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Published: 01 January 1993
Fig. 17 Effect of particle radius on energy barrier to ferrite nucleation at inclusions, Δ G * (heterogeneous), normalized relative to the homogeneous nucleation barrier, Δ G * h (homogeneous). Corresponding energy barrier to nucleation of ferrite at austenite grain boundaries is indicated More
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Published: 31 October 2011
Fig. 22 Effect of particle radius on energy barrier to ferrite nucleation at inclusions, ast; (heterogeneous), normalized relative to the homogeneous nucleation barrier, Δ G * h (homogeneous). Corresponding energy barrier to nucleation of ferrite at austenite grain boundaries is indicated More
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005410
EISBN: 978-1-62708-196-2
... a nucleating system as a homogeneous phase using the classical nucleation theory, along with heterophase fluctuations that led to the formation of precipitates. It discusses the gas cluster dynamics using the kinetic approach to describe nucleation. The article presents key parameters, such as cluster...
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Published: 31 October 2011
Fig. 7 (a) Variation in volume free-energy with temperature for the solid and liquid. (b) Variation in surface energy term, volume free-energy term, and Δ G hom with nucleus radius for homogeneous nucleation More
Series: ASM Handbook
Volume: 3
Publisher: ASM International
Published: 27 April 2016
DOI: 10.31399/asm.hb.v03.a0006222
EISBN: 978-1-62708-163-4
.... This process of forming nuclei in the freezing melt and their subsequent growth is characterized as a nucleation and growth process. Fig. 13 Nucleation and growth during solidification. Source: Ref 2 Nucleation can occur by either homogeneous or heterogeneous nucleation. Homogenous nucleation...
Series: ASM Handbook
Volume: 4E
Publisher: ASM International
Published: 01 June 2016
DOI: 10.31399/asm.hb.v04e.a0006250
EISBN: 978-1-62708-169-6
.... annealing castings deformation diffusion coefficient grain growth heat treatment heterogeneous nucleation homogeneous nucleation homogenization isothermal transformation nonferrous metals precipitation hardening recrystallization recrystallization temperature solid-state phase transformation...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005222
EISBN: 978-1-62708-187-0
... than that predicted using the lever rule ( Ref 9 ). This accounts for the observation that gas porosity occurs in alloys with initial gas concentrations lower than the solubility of the gas in the liquid. Porosity Formation Homogeneous Nucleation Similar to the nucleation of any phase...
Series: ASM Handbook
Volume: 1A
Publisher: ASM International
Published: 31 August 2017
DOI: 10.31399/asm.hb.v01a.a0006304
EISBN: 978-1-62708-179-5
... is an extension of the steady-state homogeneous nucleation theory, fail to match experimental data because the mechanisms of the two types of nucleation are different ( Ref 2 ). Homogeneous nucleation results from the stabilization of a transient grouping of atoms, so that a nucleus consisting of many atoms...
Series: ASM Handbook
Volume: 6A
Publisher: ASM International
Published: 31 October 2011
DOI: 10.31399/asm.hb.v06a.a0005609
EISBN: 978-1-62708-174-0
... Figure 6 compares examples of homogeneous nucleation in a liquid ( Fig. 6 ) and heterogeneous nucleation on a preexisting mold wall ( Fig. 6 ). The change in free energy associated with homogeneous nucleation (Δ G hom ) is given by ( Ref 4 ): (Eq 3) Δ G hom = − V s Δ G v...
Series: ASM Handbook
Volume: 6
Publisher: ASM International
Published: 01 January 1993
DOI: 10.31399/asm.hb.v06.a0001338
EISBN: 978-1-62708-173-3
... . There are three ways in which a solid can form: homogeneous nucleation, heterogeneous nucleation, and epitaxial growth. Homogeneous nucleation occurs when there is no foreign body (mold wall, solid particle in the melt, etc.) on which to form the solid. Figure 2 shows the balance of the surface tension...
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Published: 01 December 2004
Fig. 4 Miscibility gap. Region 1: homogenous α is stable. Region 2: homogenous α is metastable, only incoherent phases can nucleate. Region 3: homogeneous α metastable, coherent phases can nucleate. Region 4: homogeneous α unstable, spinodal decomposition occurs. Source: Ref 4 More
Image
Published: 27 April 2016
Fig. 16 Miscibility gap. Region 1: Homogenous α is stable. Region 2: Homogenous α is metastable; only incoherent phases can nucleate. Region 3: Homogeneous α is metastable; coherent phases can nucleate. Region 4: Homogeneous α is unstable; spinodal decomposition occurs. Source: Ref 10 More
Series: ASM Handbook
Volume: 9
Publisher: ASM International
Published: 01 December 2004
DOI: 10.31399/asm.hb.v09.a0003732
EISBN: 978-1-62708-177-1
... ). Fig. 4 Miscibility gap. Region 1: homogenous α is stable. Region 2: homogenous α is metastable, only incoherent phases can nucleate. Region 3: homogeneous α metastable, coherent phases can nucleate. Region 4: homogeneous α unstable, spinodal decomposition occurs. Source: Ref 4...
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005432
EISBN: 978-1-62708-196-2
... the assumptions of the JMAK theory: Randomly distributed and homogeneous nucleation Either site saturated or constant nucleation rate Constant and isotropic growth rate Compared to the well-known JMAK results, the kinetics f recrystallization are adequately reproduced, apart from minor...