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nonequilibrium back diffusion solidification

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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
... solidification nonequilibrium Gulliver-Scheil solidification nonequilibrium back diffusion solidification microsegregation kinetics titanium-molybdenum isomorphous systems aluminum-copper eutectic systems aluminum-silicon eutectic systems copper-zinc peritectic systems Al-Si-Cu-Mg eutectic systems Fe-C...
Series: ASM Handbook
Volume: 4E
Publisher: ASM International
Published: 01 June 2016
DOI: 10.31399/asm.hb.v04e.a0006257
EISBN: 978-1-62708-169-6
... is on the order of minutes or longer. With solid-state diffusion being many orders of magnitude lower than diffusion in the liquid, the typical situation is that the liquid is well mixed while the solid is not. Considering the nonequilibrium solidification of the alloy in Fig. 3 , as the temperature is reduced...
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
.... Example shown is for a simple eutectic system that forms primary α phase and intercellular α/β eutectic under conditions of nonequilibrium solidification. Location of composition trace is across primary and eutectic α phase, as shown by horizontal dotted line. On a microscopic scale, there can also...
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
... that different degrees of departure from equilibrium constitute a hierarchy that corresponds to increasing solidification rate ( Ref 4 ): full diffusional (global) equilibrium, local interfacial equilibrium, metastable local interfacial equilibrium, and interfacial nonequilibrium. Full Diffusional (Global...
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
... of peritectic alloys is usually very large. Referring back to Fig. 1 , the β phase, in forming from the liquid and α phases, surrounds or encases the α-phase particles. This surrounding or encasement shields the α phase from further reaction with the liquid, and diffusion in the solid phases is usually...
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
..., as well as the nonequilibrium effects. casting solidification supercooling model weld microstructure welding OF ALL PHASE TRANSFORMATIONS, few have been more widely observed and studied than the transformation of a liquid to a solid (that is, solidification). The process of solidification...
Series: ASM Handbook
Volume: 3
Publisher: ASM International
Published: 27 April 2016
DOI: 10.31399/asm.hb.v03.a0006224
EISBN: 978-1-62708-163-4
..., predictions of the lever model are closer to reality. Modeling of real solidification behavior requires knowledge of the temperature dependence of the partition coefficients and liquidus slopes and a kinetic analysis of microsegregation and back diffusion at each temperature. An example of a type...
Series: ASM Handbook
Volume: 22B
Publisher: ASM International
Published: 01 November 2010
DOI: 10.31399/asm.hb.v22b.a0005511
EISBN: 978-1-62708-197-9
... assumes phase equilibrium at the liquid-solid interface, no back diffusion in the solid, and complete mixing in the liquid. With these assumptions, only the phase equilibrium information is needed as input for carrying out solidification simulation. By using this model, which has been implemented...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005206
EISBN: 978-1-62708-187-0
... solidification behavior requires knowledge of the temperature dependence of the partition coefficients and liquidus slopes and a kinetic analysis of microsegregation and back diffusion at each temperature. The solidification of a binary alloy is schematically shown in Fig. 4 (the sketches...
Series: ASM Handbook
Volume: 22B
Publisher: ASM International
Published: 01 November 2010
DOI: 10.31399/asm.hb.v22b.a0005517
EISBN: 978-1-62708-197-9
... the eutectic composition, and final solidification will occur via this reaction. Any appearance of secondary phases can be easily taken into account in this approach if it assumed that no back diffusion occurs in them. Therefore, all transformations can be accounted for, including the final eutectic...
Series: ASM Handbook
Volume: 1A
Publisher: ASM International
Published: 31 August 2017
DOI: 10.31399/asm.hb.v01a.a0006299
EISBN: 978-1-62708-179-5
... the first deviation from a constant cooling rate on the solidification curve ( Fig. 1 ). During further cooling, more austenite is formed at the same time recovery is occurring in the already-formed solid phase. There also is some back diffusion of alloys into the solid phase. The fraction of solid...
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
... evolution of the structure. To calculate this evolution, conservation equations are written for each individual phase (liquid or solid), with the most challenging aspect being the treatment of the interfaces between phases and the nonequilibrium condition of the liquid metal during the solidification state...
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
... challenging aspect being the treatment of the interfaces between phases and the nonequilibrium condition of the liquid metal during the solidification state. The microstructure of a casting can consist of different grains of the same thermodynamic phase, distinct by orientation, or different phases of one...
Series: ASM Handbook
Volume: 9
Publisher: ASM International
Published: 01 December 2004
DOI: 10.31399/asm.hb.v09.a0003723
EISBN: 978-1-62708-177-1
... their ability to interpret microstructures after reading this article. The main concepts that a study of physical metallurgy provides include phase transformations, such as solidification and solid-state transformations such as the eutectoid and the martensitic types; the role of diffusion rate in promoting...
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003171
EISBN: 978-1-62708-199-3
... to reach the areas where solidification is occurring. As a result, tiny micropores form between the equiaxed grains. This condition is known as microporosity. Effects of Nonequilibrium Conditions The discussion to this point has assumed that solidification takes place under equilibrium conditions...
Series: ASM Handbook
Volume: 6
Publisher: ASM International
Published: 01 January 1993
DOI: 10.31399/asm.hb.v06.a0001421
EISBN: 978-1-62708-173-3
.... The process employs a filler material or interlayer to produce a transient liquid layer at the interface to be joined. Solidification of the joint occurs isothermally, by diffusion. The advantage of TLP bonding of Al-MMCs involves the lower peak-processing temperatures, compared with the temperatures used...
Series: ASM Handbook
Volume: 22B
Publisher: ASM International
Published: 01 November 2010
DOI: 10.31399/asm.hb.v22b.a0005501
EISBN: 978-1-62708-197-9
... for casting alloys is introduced in which back diffusion is included so that the cooling condition can be accounted for. Then, a brief review of the calculation of thermophysical properties is presented. Fundamentals of the modeling of solidification processes are discussed next. The modeling conservation...
Book Chapter

By W.L. Johnson
Series: ASM Handbook
Volume: 2
Publisher: ASM International
Published: 01 January 1990
DOI: 10.31399/asm.hb.v02.a0001095
EISBN: 978-1-62708-162-7
...-film diffusion couple consisting of layers of nickel and zirconium. (a) The diffusion couple has been reacted at 300 °C (570 °F) for 6 h. An amorphous interlayer having a thickness of about 80 nm has formed and grown at the nickel-zirconium interface. (b) The diffusion couple has been reacted for 18 h...
Series: ASM Handbook
Volume: 6A
Publisher: ASM International
Published: 31 October 2011
DOI: 10.31399/asm.hb.v06a.a0005588
EISBN: 978-1-62708-174-0
..., the latter of which is of greater metallurgical interest. Hot cracking usually begins in the transient zone, because of the nonequilibrium solidification of the base material. A crack that forms in the source-initiation stage may propagate along the weld if the solidification strains sufficiently multiply...
Series: ASM Handbook
Volume: 22B
Publisher: ASM International
Published: 01 November 2010
DOI: 10.31399/asm.hb.v22b.a0005518
EISBN: 978-1-62708-197-9
... spacing is also required for the calculation of microsegregation and the solidification path, because it determines the influence of back diffusion and thus the composition of the remaining liquid. Fluid flow calculations in solidification processes also require an estimation of the secondary arm spacing...