Foundations of Materials Science and Engineering
6th Edition
ISBN: 9781259696558
Author: SMITH
Publisher: MCG
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Chapter 4.8, Problem 3KCP
In the solidification of a pure metal, what are the two energies involved in the transformation? Write the equation for the total free-energy change involved in the transformation of liquid to produce a strain-free solid nucleus by homogeneous nucleation. Also, illustrate graphically the energy changes associated with the formation of a nucleus during solidification.
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4. Johnston and Gilman reported that in a grown LiF crystal that has been subjected to a constantstress of 10.8 MPa, the dislocation velocity at 249.1 K was 6×10-3 cm/s and at 227.3 K thevelocity was 10-6 cm/s. They also observed that their data suggested an Arrhenius relationshipbetween the dislocation velocity and the absolute temperature so that we can write? = ?exp ( ― ?/??)where v is the dislocation velocity, A is a constant of proportionality, Q an effective activationenergy in J/mol, and R is the universal gas constant (8.314 J/mol.K). Determine Q and A usingthe given data and the above equation.
5. A typical cross-head speed in a tensile testing machine is 0.2 in./min.
(a) What is thenominal/engineering strain rate imposed by this cross-head speed on a typical engineering tensilespecimen with a 2 inch gauge length?
(b) Estimate the average dislocation velocity that would be obtained at this strain rate in analpha-iron specimen with a total dislocation density of 1010 cm-2 of…
Q1/ In a homogeneous solidification process, assume molten metal solidifies into a spherical
nucleus with a BCC structure. The given data are; lattice parameter (0.292 nm), the heat of
fusion energy (1.85×10-9 J/m³), latent surface free energy (0.204 J/m²), critical radius (1-35
nm), equilibrium melting temperature (1516 K), and room temperature (27 °C). Calculate the
following for this metal;
(a) supercooling value temperature (b) activation tree energy (c) number of atoms in a
nucleus of critical size.
Question-6. For solidification of a piece of FCC-metal at 860 °C. The melting point of the metal
is 1260 °C. The latent heat of fusion and surface free energy are -2.16 x108 J/m³ and 0.126 J/m²,
respectively. If nucleation is homogeneous, answer the following questions:
(a) Compute the critical radius r* in nm
(b) Compute the activation free energy AG* in J
(c) If the lattice parameter is 0.26 nm at the melting temperature, compute the number of atoms
found in a nucleus of critical size
(d) Compute the critical radius at the supercooling degree of 260 K.
Chapter 4 Solutions
Foundations of Materials Science and Engineering
Ch. 4.8 - Prob. 1KCPCh. 4.8 - Define the homogeneous nucleation process for the...Ch. 4.8 - In the solidification of a pure metal, what are...Ch. 4.8 - In the solidification of a metal, what is the...Ch. 4.8 - During solidification, how does the degree of...Ch. 4.8 - Distinguish between homogeneous and heterogeneous...Ch. 4.8 - Describe the grain structure of a metal ingot that...Ch. 4.8 - Distinguish between equiaxed and columnar grains...Ch. 4.8 - How can the grain size of a cast ingot be refined?...Ch. 4.8 - Prob. 10KCP
Ch. 4.8 - Prob. 11KCPCh. 4.8 - Prob. 12KCPCh. 4.8 - Distinguish between a substitutional solid...Ch. 4.8 - What are the conditions that are favorable for...Ch. 4.8 - Prob. 15KCPCh. 4.8 - Prob. 16KCPCh. 4.8 - Prob. 17KCPCh. 4.8 - Prob. 18KCPCh. 4.8 - Describe the structure of a grain boundary. Why...Ch. 4.8 - Describe and illustrate the following planar...Ch. 4.8 - Prob. 21KCPCh. 4.8 - Describe the optical metallography technique. What...Ch. 4.8 - Prob. 23KCPCh. 4.8 - Prob. 24KCPCh. 4.8 - Prob. 25KCPCh. 4.8 - Prob. 26KCPCh. 4.8 - Prob. 27KCPCh. 4.8 - Prob. 28KCPCh. 4.8 - Prob. 29KCPCh. 4.8 - Prob. 30KCPCh. 4.8 - Prob. 31KCPCh. 4.8 - Calculate the size (radius) of the critically...Ch. 4.8 - Prob. 33AAPCh. 4.8 - Prob. 34AAPCh. 4.8 - Calculate the number of atoms in a critically...Ch. 4.8 - Prob. 36AAPCh. 4.8 - Prob. 37AAPCh. 4.8 - Prob. 38AAPCh. 4.8 - Prob. 39AAPCh. 4.8 - Prob. 40AAPCh. 4.8 - Prob. 41AAPCh. 4.8 - Prob. 42AAPCh. 4.8 - Determine, by counting, the ASTM grain-size number...Ch. 4.8 - Prob. 44AAPCh. 4.8 - For the grain structure in Problem 4.43, estimate...Ch. 4.8 - Prob. 46AAPCh. 4.8 - Prob. 47SEPCh. 4.8 - Prob. 48SEPCh. 4.8 - Prob. 49SEPCh. 4.8 - Prob. 50SEPCh. 4.8 - In Chapter 3 (Example Problem 3.11), we calculated...Ch. 4.8 - Prob. 52SEPCh. 4.8 - Prob. 53SEPCh. 4.8 - Prob. 54SEPCh. 4.8 - Prob. 55SEPCh. 4.8 - Prob. 56SEPCh. 4.8 - Prob. 57SEPCh. 4.8 - Prob. 58SEPCh. 4.8 - Prob. 59SEPCh. 4.8 - Prob. 60SEPCh. 4.8 - Prob. 61SEPCh. 4.8 - Prob. 62SEPCh. 4.8 - Prob. 63SEPCh. 4.8 - Prob. 64SEPCh. 4.8 - Prob. 65SEPCh. 4.8 - Prob. 66SEP
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Explanation of Solidification of Metals & Alloys | Manufacturing Processes; Author: Magic Marks;https://www.youtube.com/watch?v=G5z9KknF_s8;License: Standard Youtube License