Final answer:
The question concerns the similarities and differences between interstitial diffusion and vacancy diffusion in materials engineering. Interstitial diffusion involves smaller atoms moving through spaces in a crystal lattice, while vacancy diffusion involves atoms moving into missing spots within the lattice. Contrary to the assertions in the question, interstitial diffusion typically has lower activation energy and is not restricted to gases.
Step-by-step explanation:
Comparing interstitial diffusion and vacancy diffusion, both indeed involve atom movement within solids, primarily metals or alloys. However, there are notable differences between the two:
- Interstitial diffusion occurs when smaller atoms or ions move through the interstices (small spaces) between the larger atoms in a crystal lattice.
- Vacancy diffusion involves atoms or ions moving into vacancies or holes where an atom is missing in the crystal lattice.
Concerning the choices provided in the question:
- Both A) and C) are incorrect. Interstitial diffusion typically has a lower activation energy compared to vacancy diffusion because it's easier for smaller atoms to move through the interstices than for atoms to jump into vacant lattice sites. Hence, it is not accurate to say that interstitial diffusion has a higher activation energy or that vacancy diffusion is generally faster.
- B) and D) are also incorrect. Interstitial diffusion is not restricted to gases; it occurs in solids as well, such as when carbon or nitrogen atoms diffuse through iron to form steel.