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dendrite arm spacing

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Series: ASM Handbook
Volume: 5B
Publisher: ASM International
Published: 30 September 2015
DOI: 10.31399/asm.hb.v05b.a0006012
EISBN: 978-1-62708-172-6
... conducted in different types of nanomaterials. Materials containing CNTs (single wall and multilayer), which typically have an internal diameter of 5 nm and external diameter of 10 nm, have the potential to become 50 to 100 times stronger than steel at one-sixth the weight. Future applications include space...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005229
EISBN: 978-1-62708-187-0
..., diffusing distance (i.e., secondary dendrite arm space), diffusivity of solutes, dissolution rate, and so on. In general, cast nonferrous alloys (both heat treatable and non-heat treatable) and ferrous alloys are homogenized at temperatures 20 to 100 °C (36 to 180 °F) below the solidus temperature. Care...
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
... characteristic parameters that can be quantitatively measured and can be related to properties. For equiaxed dendritic structure, the important characteristic lengths of the microstructure are the dendrite tip radius, R , the secondary arm spacing, λ 2 , and the average distance between the grains. For...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005237
EISBN: 978-1-62708-187-0
... ) where α is a Fourier diffusion number, defined as D S t f /4λ 2 ; D S is the diffusion coefficient of the solute in the solid; t f is the solidification time; and λ is the dendritic length scale (often taken as the secondary dendrite arm spacing). It is assumed that k and α are constant...
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003171
EISBN: 978-1-62708-199-3
... from the primary arm. The spacing of the secondary arms is proportional to the rate at which heat is removed from the casting during solidification. Each crystal consists of a single dendrite. Fig. 5 Growing dendrite tip and dendrite root during columnar growth in a casting. A dendritic form is...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005339
EISBN: 978-1-62708-187-0
..., on dendrite formation and microsegregation, is discussed in some detail. Figure 11 shows the effect of alumina fiber spacing on the microstructure of Al-4.5% Cu alloy ( Ref 25 ). The primary phase morphology and distribution of second phases depend on the relative magnitudes of dendrite arm...
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
... , is approximated by one-half the final dendrite arm spacing (das) for the local region of the casting under consideration ( Ref 1 , 2 , 3 , 4 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ). For a highly grain-refined casting, one-half the grain size could...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005208
EISBN: 978-1-62708-187-0
... primary dendrite arm spacing. These equations are partially scaled by defining ζ = z /λ 1 , with the result: (Eq 28) − ( v n * λ 1 α ) ∂ T ∂ ζ = ∂ 2 T ∂ ζ 2 (Eq 29) − ( v n * λ 1 D L ) ∂ C L ∂ ζ = ∂ 2...
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005437
EISBN: 978-1-62708-196-2
... ∂ 2 C L ∂ z 2 0 ≤ z (Eq 27) − v n ∗ ∂ C s ∂ z = D s ∂ 2 C s ∂ z 2 z ≤ 0 Looking at the micrograph in Fig. 3 , it seems that the system chooses a length scale λ 1 , the primary dendrite arm spacing. These...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005216
EISBN: 978-1-62708-187-0
... forming, which often consists of dendrites having arm spacings of the order of 10 to 100 μm. It is therefore termed microsegregation and results in a nonuniform, cored solute distribution in the dendrite arms. Consider now a small volume element that contains several dendrite arms and the liquid between...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005348
EISBN: 978-1-62708-187-0
... diffusion coefficient in solid da/dN fatigue crack growth rate DAS dendrite arm spacing dc direct rent DCEP direct current electrode positive DCRF Die Casting Research Foundation diam diameter DIS Draft International Standard DOC Department of Commerce...
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
... Optical micrographs showing nucleation of silicon phase (a) on graphite particle and (b) on nickel-coated graphite particles in hypereutectic aluminum-silicon alloys The primary phase morphology and the distribution of second phases depend on the relative magnitudes of dendrite arm spacing and...
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
..., tracer diffusivity can be used to formulate an estimate of the time required to solve the diffusion problem: ∼ x 2 D where D is diffusivity, and x is the diffusion distance (in this case, taken as half the secondary dendrite arm spacing). Because the diffusivity has the form of: D...
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
... possibly average dendrite arm spacings, within the casting. It consequently does not directly provide a map of the structure. The typical representative elementary volume (REV) of such macroscopic scale method is shown in Fig. 1 . It contains several grains or phases that are not resolved on 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
... a control volume (CV) or finite element (FE) method. The results of such models are average grain sizes, and possibly average dendrite arm spacings, within the casting. It consequently does not directly provide a of the structure. The typical representative elementary volume (REV) of such...
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
... chills are properly used for feeding the liquid shrinkage. Increasing the cooling rate can increase the temperature gradient at the freezing front, making the feeding channel open and wide. Furthermore, the radius of a pore is usually proportional to the secondary dendrite arm spacing, which decreases...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005269
EISBN: 978-1-62708-187-0
... shrink porosity due to high cavity pressure (70 to 100 MPa, or 10 to 15 ksi) and rapid solidification rate (from the contact of the molten metal with the lubricated die surface) Smaller dendrite arm spacing and a fibrous eutectic silicon morphology resulting from the rapid solidification rate Heat...
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003127
EISBN: 978-1-62708-199-3
... dendrite-arm spacing (DAS), the most convenient feature for metallographic measurement and quantification, are closely correlated with constituent size and the effects on strength and ductility. Nominal DAS values are listed for three casting processes (sand, permanent mold, and die casting) in Table 2...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005234
EISBN: 978-1-62708-187-0
... complexity lurking in the treatment of the permeability. A common approach is to use the Blake-Kozeny model for permeability in terms of solid volume fraction g 1 and dendritic arm spacing ( d ). Assuming the mushy region morphology forms an isotropic medium: (Eq 24) K = d 2 180 g...
Series: ASM Handbook
Volume: 12
Publisher: ASM International
Published: 01 January 1987
DOI: 10.31399/asm.hb.v12.a0000614
EISBN: 978-1-62708-181-8
... arms are oriented horizontally. See also Fig. 804 and 805 . SEM, 270× Fig. 804 Lower-magnification view of the exposed dendrites in the shrinkage cavity in the cast specimen of 18% Ni, grade 300, maraging steel in Fig. 803 , showing dendrites that formed at different orientations. Had...