{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Chap9_2pgs - =24 in.z t = 4.6 =B(8D4\2 B =4.61(0.333)2 =...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Princlple$ uf $olldlfhntlon 9-10 Suppose that liquid nickel is undercooled until homogeneous nucleation occurs. Ca'tcutate (a) ttri critical radius of the nucleus required,and (b) the number of nickel atoms in the nucleus. Assume that the lattice parameter of the solid FCC nickel is 0.356 nm. Solution: From Table 9-1, Afmsx = 48fC r*= (2)(255 x 10-7 J/cm2)(1453 +273) = 6.65 x l0r8 cm (2756 J/cm3)(480) | =45.118 x t0-24 cm3 %u"l"u. = (4Tc13X6.65 x 10-8 cm)3 = I232x l0-2a cm3 number of unit cells = 1232145.11$ = 27.3 atoms per nucleus = (4 atomVcellX2T.3 cells) = 109 atoms CHAPTER 9 Principles of Solidification 85 9-31 A 2-in. cube solidifies in 4.6 min. Calculate (a) the mold constant in Chvorinov's rule and (b) the solidification time for a 0.5 in. x 0.5 in. x 6 in. bar cast under the same conditions. Assume that n = 2. Solutlon: (a) We can find the volume and surface area of the cube: V = (2)t= 8 in.3 A
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: =24 in.z t = 4.6 =B(8D4\2 B =4.61(0.333)2 = 41.48 min/in.2 (b) For the bar, assuming that B = 41.48 minfn.2: Y= (0.5X0.5)(6) = 1.5 in.2 A = 2(0.5X0.5) + 4(0.5)(6) = 12.5 in.2 1= (41.48)(1.5112.5\2 = 0.60 min Qo=3'56 A 945 A cooling curve is shown in Figure 9-2|.Determine (a) the pouring temperature, (b) the solidification temperature, (c) the superheat, (d) the cooling ratejust before solidification begins, (e) the total solidification time, (f) the local solidification time' and (g) the probable identity of the metal. (h) If the cooling curve was obtained at the center of the casting sketched in the figure, determine the mold constant, assum' ingthatn=2. Solution: (a) Toou , = 47 soc (b) ?Lr = 32oPc (c) 47" = 475 - 320 = 155oC 475 - 320 (d)4nfu1 = ,rr* =1.0oC/s ( e ) f = 4 7 0 s (f) LST = 470 - 170 = 300 s (g) Cadmium (Cd) (h) r, = 470 = B[38 .4t121.612 B - 4713 s/cmz...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern