CHAPTER 5 in Materials science and Engineering, Please answer the question with

Question

CHAPTER 5 in Materials science and Engineering, Please answer the question with clear hand writing or if you are going to write it in your comptuer please use "insert equastion" feature, otherwise even if you were first but someone else came up with this will get the points.

A number of metals such as Fe and Co may have different structures under same conditions. At a certain elevated temperature, it is known that one such metal may exist in FCC or BCC form. The diffusion coefficients for the inter-diffusion of C in this metal at this elevated temperature are 1.82 times 10-9 ft2 s-1 and 6.31 times 10-11 ft2 s-1 respectively. Suggest which diffusion coefficient is for FCC and which is for BCC. And explain why.

Explanation / Answer

the packing factor for FCC = 8*1/8 + 6*1/2 = 4

whereas for BCC lattice = 8*1/8 + 1 = 2

so the BCC lattice allows more volume for the inter diffusion of C in the metal lattice therefore the rate 1.82*10^-9 ft^2s^-1 being higher is for BCC lattice and 6.31*10^-11 ft^2s^-1 being lower is for FCC lattice which has a higher packing fraction

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---