An analysis of the microstructure of rapidly solidified Al-8 wt pct Fe powder

Boettinger, William J.; Bendersky, Leonid A.; Early, J G

doi:10.1007/bf02643853

Cited by 136 publications

(31 citation statements)

References 13 publications

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“…In a recent study (32) of the microstructure of Al-8wt% Fe powder atomized by the Homogeneous Metals Co., transitions of microstructure as a function of powder diameter were found to be extremely consistent with the previous work of Hughes and Jones (33) using directional solidification. They showed that the microstructure of Al-6 wt% Fe changes from a primary intermetallic structure of A13Fe to fully eutectic structure of a-AI + A16Fe and finally to a cellular structure of a-AI in the range of velocity between 0.1 and 1 cm/s.…”

supporting

confidence: 82%

“…Nucleation appears to have occurred at a single site on the surface of the particle on the left and the solidification front has passed from left to right. The microstructure near the point of nucelation is extremely fine and is termed microcellular (32).The microstructure on the right is a more usual coarse cellular structure of a-AI.…”

Section: The Microstructure Of Initially Undercooled Powdersmentioning

confidence: 99%

“…Slightly higher transition velocities would be expected for Al-8 wt% Fe powders. An identical change in microstructure is observed for AI-8wt%Fe powders with diameters between 50 and 10 ~ where the estimated growth rate changes as a function of powder diameter from 0.2 to 1 cm/s as analyzed for the Homogeneous Metals process (32). Additionally Hughes and Jones (33) measured theA 2 V constant which relates the eutectic spacing, A , to the growth rate for the a-AI + A~Fe eutectic as a function of iron content.…”

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confidence: 90%

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Microstructure Formation in Rapidly Solidified Alloys

Boettinger

Coriell

1986

Science and Technology of the Undercooled Melt

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ABSTRAcr 81In order to apply solidification theory to the interpretation of microstructures produced by rapid solidification, several modifications are required. Different degrees of non-equilibrium occur during solidification and constitute a hierarchy which is followed with increasing solidification rate.Analytical expressions are given for a model of non-equilibrium interface conditions which describe the temperatures and compositions at the liquid solid interface as a function of solidification velocity. For solidification at intermediate veloici ties ('" 1 0 cm/ s) the assumption of local interfacial equilibrium remains valid but microstructures are often produced under conditions where the solute Peclet number Pc = Vl/2D, is greater than one. '!he parameters V, 1 and D are the solidification velocity, relevant microstructural length scale and liquid diffusion coefficient respectively. '!his fact requires that several topics in solidification theory be modified. SUch a modification is presented for alloy dendritic growth theory. For alloys solidifying dendri tically into undercooled melts, solute redistribution dominates the relatinship between growth rate and initial undercooling when the initial undercooling is smaller than the alloy freezing range (difference between liquidus and solidus temperatures). '!his fact has several important consequences for the eutectic coupled zone boundaries and for arrayed dendritic growth.

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confidence: 82%

Section: The Microstructure Of Initially Undercooled Powdersmentioning

confidence: 99%

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confidence: 90%

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Microstructure Formation in Rapidly Solidified Alloys

Boettinger

Coriell

1986

Science and Technology of the Undercooled Melt

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“…The microstructure with fine cells, without dendrite, also have been reported in small alloy droplets. 3,4) In this figure we can see solute-bands parallel to the advancing interface on macroscopic view, which are related with the bumps in curve (d) of Fig. 3.…”

Section: Non-isothermal Solidificationmentioning

confidence: 98%

“…[1][2][3][4][5] The solidification patterns in rapid solidification of alloy droplets are dependent on the heat transfer coefficient between droplet surface and external coolant, h and the undercooling just before onset of nucleation, DT. When a large h or high DT is given, the partitionless solidification with complete solute trapping often occurs first and then the interface pattern is developed into cellular and dendritic mode with recalescence.…”

Section: Introductionmentioning

confidence: 99%

Phase-field Modeling of Rapid Solidification in Small Alloy Droplets

Kim

Suzuki

2003

ISIJ International

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Phase field modeling has been applied first to simulate microstructural evolution during rapid solidification of small Al-0.02 mole fraction Cu alloy droplets. We use a phase-field model with the parameters determined at a finite interface thickness condition. Numerical computation is stable over a wide temperature range because same interface energy and interface thickness are applied during computation by using temperature dependence of phase field parameters. For numerical efficiency, we adopted rather thick interface thickness, large interface energy and small interface kinetics coefficient, compared with reported values. Nevertheless, overall features of microstructural evolution presented in this study show close resemblance with the reported theoretical predictions and experimental results; initial dendrite/plane-front transition when the nucleation undercooling is small, plane-front/cell and cell/dendrite transition in high interface velocity regime, complete disappearance of dendritic structure in high heat transfer coefficient and deflection phenomena in cellular growth direction.

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