1 / 17

Try not to have a good time...this is supposed to be educational -Peanuts

Try not to have a good time...this is supposed to be educational -Peanuts. Example - 718 Ni-base superalloy. Composition: 52.5Ni 19Cr 3Mo 19Fe 0.4Al 5Nb-1Ti 0.04C . Example - 718 Ni-base superalloy. Example - 718 Ni-base superalloy. Example - 718 Ni-base superalloy.

lucius
Télécharger la présentation

Try not to have a good time...this is supposed to be educational -Peanuts

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Try not to have a good time...this is supposed to be educational -Peanuts

  2. Example - 718 Ni-base superalloy Composition: 52.5Ni 19Cr 3Mo 19Fe 0.4Al 5Nb-1Ti 0.04C

  3. Example - 718 Ni-base superalloy

  4. Example - 718 Ni-base superalloy

  5. Example - 718 Ni-base superalloy Possibilities for strengthening 718:

  6. Example - 718 Ni-base superalloy

  7. Example - 718 Ni-base superalloy 52.5Ni Provides friendly matrix for alloying elements 19Cr Oxidation and corrosion resistance, solid solution strengthening 3Mo Solid solution strengthening, stabilizes chromium oxide film, carbide formation for Hi T strength 19Fe Solid solution strengthening 0.4Al Increases oxidation resistance, forms strengthening pptates 5Nb-1Ti Form strengthening pptates 0.04C Carbide formation for creep resistance

  8. Diffusion concn concn concn concn distance distance distance distance Movement of atoms (or molecules) down a concentration gradient How??

  9. Diffusion Vacancies occur naturally in materials vacancy One way - vacancy movement No. fract. of vacancies = exp (-Q/RT)

  10. Diffusion Vacancies occur naturally in materials vacancy One way - vacancy movement No. fract. of vacancies = exp (-Q/RT) For Cu @ rm T: 1/1014; @ 1080°C: 1/1600

  11. Diffusion Vacancy movement

  12. Diffusion concn concn concn concn distance distance distance distance Movement of atoms (or molecules) down a concentration gradient I lied

  13. Diffusion Movement of atoms (or molecules) over a hump Where do we get the activation energy?

  14. Diffusion Where do we get the activation energy? From energy stored as thermal vibrations # jumps/sec = A exp (-Q/RT) For Cu: # jumps/sec = 1015 exp (-29/RT) = 1.1 x 10-6 @ rm T = 2.2 x 1010 @ 1080° C

  15. Diffusion Diffusion coefficient: flux J = D(T) dC/dx D(T) = Do exp (-Q/RT) For C diffusing in Fe: D(T) = 0.21 exp (-33.8/RT) = 6.7 x 10-11 cm2/sec @ 500° C = 4 x 10-7 cm2/sec @ 1000° C

  16. Diffusion For C diffusing in Fe: D(T) = 0.21 exp (-33.8/RT) = 6.7 x 10-11 cm2/sec @ 500° C = 4 x 10-7 cm2/sec @ 1000° C Ex - carburizing a steel shaft: how long to carburize to depth of 1 mm x2 = D t D(1000° C) = 3 x 10-7 cm2/sec t = 10 hr D(1200° C) = 1.8 x 10-6 cm2/sec t = 1.5 hr

  17. Assignments for next class: 1. review today's classnotes a. vacancies & vacancy motion b. rates of diffusion in solids c. effect of temperature on diffusion rates d. carburization example 2. Read text: chapter 5

More Related