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kinetic undercooling

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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
... model, free growth model, and constitutional undercooling model. The article concludes with a section on thermal analysis techniques for assessing grain-refining characteristics during master alloy processing. casting heterogeneous nucleation homogeneous nucleation nucleation kinetics...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005226
EISBN: 978-1-62708-187-0
... formation of noncrystalline phases. It considers three factors: heat flow, thermodynamic constraints/conditions at the liquid-solid interfaces, and diffusional kinetics/microsegregation, to understand the fundamentals of these changes. These factors are described in detail. casting microsegregation...
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
... transformations and free energy, as well as kinetics of phase transformations. It concludes with a description of solid-state phase transformations that occur when one or more parent phases, usually on cooling, produces a phase or phases. free energy intermediate phases interstitial solid solutions...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005215
EISBN: 978-1-62708-187-0
... requires that there must be (1) negligible undercooling before the nucleation of the solid phases; (2) negligible undercooling at the solid-liquid interface due to curvature, interface kinetics, or a solute boundary layer (local equilibrium at the solid-liquid interface); (3) sufficient mass transport in...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005213
EISBN: 978-1-62708-187-0
... they are displaced to greater undercoolings ( Fig. 23 ). Another theory relates graphite shape in cast iron with undercooling (kinetic plus constitutional) during solidification ( Ref 6 ). As shown in Fig. 24 , each graphite form has its own temperature for growth, which is achieved by a specific...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005209
EISBN: 978-1-62708-187-0
... is superimposed on the temperature field due to the heat flux (neglecting a very small undercooling from atom attachment kinetics), an undercooled liquid region is obtained under certain conditions. The concentration gradient for the steady-state concentration field ( Eq 6 ) at the interface z...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005210
EISBN: 978-1-62708-187-0
... important in determining the microstructure of the cast alloy. Two distinctly different conditions may exist in a mold that can give rise to equiaxed or columnar crystals. First, consider the case of equiaxed crystals that form in an undercooled melt. As the solid nucleates and grows, latent heat and solute...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005227
EISBN: 978-1-62708-187-0
... repulsive force and fluid drag as attractive force; shape-preserving paraboloidal growth front; considers smooth particles and thermal conductivities of particle and melt; neglects kinetic undercooling; solute screening is considered separately Stefanescu et al. Repulsive surface energy and attractive...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005214
EISBN: 978-1-62708-187-0
... alloy solidifies under equilibrium conditions (the lever rule is defined in the article “Thermodynamics and Phase Diagrams” in this Volume). In practice, the lever rule usually will not give the volume fraction of the different phases, because the nucleation and growth kinetics, determined by the...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005236
EISBN: 978-1-62708-187-0
... between the solidifying mush and liquid. Applying a kinetic model for the motion of this boundary then determines the growth of the grain structure. The liquid outside a grain envelope has to stay in an undercooled state until the local REV is captured by a growing envelope, or an appropriate nucleation...
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005406
EISBN: 978-1-62708-196-2
... of the volume fraction of the phases present in the REV over time, as well as to integrate the kinetics of the development of envelopes defining the grains. Fig. 2 Schematic of a single grain ( Ref 8 ) growing in a uniform temperature field is shown in (a). The square highlighted in (a) shows a...
Series: ASM Handbook
Volume: 3
Publisher: ASM International
Published: 27 April 2016
DOI: 10.31399/asm.hb.v03.a0006226
EISBN: 978-1-62708-163-4
... from a peritectic transformation, because the nucleation and growth kinetics—determined by the diffusion rate—are slower in solid phases, increasing the time required to reach equilibrium. Fig. 3 Phase diagram with a peritectic reaction. Source: Ref 2 Peritectic reactions or...
Series: ASM Handbook
Volume: 3
Publisher: ASM International
Published: 27 April 2016
DOI: 10.31399/asm.hb.v03.a0006228
EISBN: 978-1-62708-163-4
... in two important aspects from liquid reactions in the manner in which they attain the equilibrium conditions predicted by the phase diagram. Solid-state reactions occur much more slowly, are subject to greater undercooling, and rarely attain true equilibrium conditions. Solid phases consist of atoms...
Book Chapter

Series: ASM Handbook
Volume: 3
Publisher: ASM International
Published: 27 April 2016
DOI: 10.31399/asm.hb.v03.a0006229
EISBN: 978-1-62708-163-4
... the rate of atomic migration and diffusion distances, which depend on the scale of decomposition (undercooling). The kinetic process of spinodal decomposition is illustrated in Fig. 13b , where a small fluctuation in composition becomes amplified by uphill diffusion (depicted by arrows). The reason...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005217
EISBN: 978-1-62708-187-0
... austenite. After the initial stage during the cooling down to the eutectic temperature, the lever rule will describe the fraction of solid formed. The eutectic reaction for the equilibrium case occurs without any undercooling. This deviation from equilibrium is interpreted as follows. The austenite...
Series: ASM Handbook
Volume: 4B
Publisher: ASM International
Published: 30 September 2014
DOI: 10.31399/asm.hb.v04b.a0005934
EISBN: 978-1-62708-166-5
... kinetics in aluminum alloys. An expression was derived that could be used to predict strength from the shape of a continuous cooling curve and the precipitation kinetics of the alloy being hardened ( Ref 24 , 25 , 26 ). The general technology for heat treating aluminum alloys using the quench factor...
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005414
EISBN: 978-1-62708-196-2
... deformation process, it is first necessary to develop the following models: Models for grain growth kinetics Models for recrystallization kinetics Models for recrystallized grain size Models for austenite decomposition While attempts have been made by researchers to develop physically based...
Series: ASM Handbook
Volume: 4B
Publisher: ASM International
Published: 30 September 2014
DOI: 10.31399/asm.hb.v04b.a0005936
EISBN: 978-1-62708-166-5
... along the height of specimens made of AISI 4140 (see Fig. 24 ). Source: Ref 63 In Ref 10 , the relationship between the transformation kinetics and distortion is investigated. A cylindrical specimen of AISI 5120 (German grade 20MnCr5) with a length of 160 mm (6.3 in.), cut off on one side, was...
Series: ASM Handbook
Volume: 4E
Publisher: ASM International
Published: 01 June 2016
DOI: 10.31399/asm.hb.v04e.a0006277
EISBN: 978-1-62708-169-6
... combined effects of these interacting factors, it is necessary to distinguish the roles played by each of them and, most importantly, to identify the key parameters that control the kinetics and texture evolution during grain growth. In addition to the aforementioned microstructure features, the...
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003195
EISBN: 978-1-62708-199-3
... phase transformation and annealing kinetics which establish processing times, temperatures, and cooling rates for heat treatments; and evaluation of mechanisms of deformation and fracture of the structures produced by heat treatment. In this section, an outline of the physical metallurgy associated...