(a)
Interpretation:
The critical radius of the nucleus in the liquid nickel needs to be calculated.
Concept Introduction:
Homogeneous nucleation is the process in which the nuclei that are formed randomly and spontaneously grows irreversibly and forms into a new phase.
The critical radius of the nuclei is the minimum size of the nucleus required for the formation of new stable nucleus.
Answer to Problem 9.19P
The value of the critical radius is
Explanation of Solution
From the parameter of the iron, values of different properties are:
Latent heat of fusion,
Surface free energy of solid-liquid phase,
The critical radius of homogeneous nucleation can be calculated by,
Where
Temperature difference for undercooling,
Equilibrium solidification temperature,
The equation for critical radius for homogeneous nucleation is:
Substituting the values in the equation:
Critical radius,
(b)
Interpretation:
The number of nickel atoms in the nucleus needs to be calculated.
Concept Introduction:
Homogeneous nucleation is the process in which the nuclei that are formed randomly and spontaneously grows irreversibly and form into a new phase.
Nucleus consists of different number of neutrons, protons and electrons.
Answer to Problem 9.19P
The value of a number of iron atoms in the nucleus is 109 atoms.
Explanation of Solution
Given:
The lattice parameter of solid FCC nickel,
The volume of the nucleus can be calculated by,
Where
Number of unit cell =
where
The volume of the unit cell,
The radius of the nucleus,
The volume of the nucleus,
Atoms per nucleus = (Number of the unit cell)
= 27.3
=109 atoms
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Chapter 9 Solutions
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