Nt1310 Lab 6

Question # 1:

Part A

How many electrons and protons in an atom of vanadium?

Answer # 1:

Atomic number = number of protons = 23

Mass number = number of protons + neutrons

Mass number = 51 g/mole

Number of neutrons = 51-23

Number of Neutrons = 28

Number of electrons = atomic number = 23

Question # 1:

Part B

Explain in 2 or 3 sentences how the atomic weight is what is reported.

Answer # 1: Atomic weight or atomic mass is basically the average mass of atoms of an element. Atomic mass is calculated by using the naturally occurring relative abundance of isotopes. Atomic weight determines the size of the atom. Atomic weight = mass of protons + mass of neutrons.

Question # 1:

Part C

Calculate the density of vanadium. The structure is BCC.

Answer # 2:

In general we can see from the above graph carbon diffusivity in iron is much faster as compared to aluminum diffusivity in aluminum. At about 5000C diffusivity of carbon in iron and Al in Al as shown below:

Diffusing Specie Host Metal Diffusivity (m2/sec)

Carbon α- Fe 2.4E-12

Carbon - Fe 1.7E-10

Al Al 4.2E-14

Question # 2:

Part B

At around 900oC, why is there a jump in the diffusivity value of carbon in iron?

Answer # 2: During a diffusion jump, the interstitial atom transfers from one octahedral place to another. Midway between these two places, it is bounded by 4 atoms all at equivalent spaces from the foreign atom. The 4 atoms form a tetrahedron with the foreign atom at the center. This tetrahedral place has a wall to the movement of the interstitial atom. The tetrahedral formation is the actuated state for the jump, and the structure necessity acquires activation energy to cross the energy barrier.

Question # 2:

Part C

In general carbon diffusion in iron is much “faster” than aluminum diffusion in aluminum.