Explanation Crystals consists of a huge number of defects and imperfections, usually classified as: 1. Point defects like an interstitial atom (lattice having an extra atom), a vacancy (such as missing atom), or an impurity, that is, foreign atom which has replaced the atom of the pure metal) as shown in the below Fig. 2. Linear, or 1-D (Dimension), defects are referred as dislocations. There are two types of dislocations in a single crystal: (a) Edge dislocation and (b) Screw dislocation. Here, an analogy to the movement of an edge dislocation is shown in the form of an earthworm scrolling forward by means of a hump starting at the tail and moving toward the head. Another analogy is shown moving a large carpet on a floor by first forming a hump at one end and then, moving the hump gradually to the other end. Now, remember that the force needed to move a carpet like this, is much lower than what is needed to slide the whole carpet along the floor. As the atomic planes form a spiral ramp, like the threads on a screw or bolt, we call it screw dislocation. 3. Planar, or 2-D, imperfections like phase boundaries and grain boundaries. When a mass of softened metal starts turning solid, crystals begins forming individually of each other at different locations within the liquid mass, which is why these contain random and unrelated orientations. Each of these crystals eventually grows into a crystalline grain or structure; each grain has either a single crystal (in case of pure metals) or a polycrystalline aggregate (in case it is an alloy). The generation of number and size of the grains in a unit volume of the metal varies depending on the rate of nucleation, the initial stage of forming crystal. The median size of the grains forms depending on (a) the number of different sites at which individual crystals start to form (In theFig, there are seven of those) and (b) the rate at which these crystals grow...

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The Space Lattice and Unit Cells

Every matter consists of atoms, molecules, and ions. If these atoms, molecules, and ions (micro-particles) are represented in a three-dimensional space-occupying certain specific points in space, then these arrangements are termed as space lattices and t…

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Chapter 1, Problem 9RQ

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Enlist every major types of imperfection in the crystal structure of metals, and elaborate the same.

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Chapter 1 Solutions

EBK MANUFACTURING ENGINEERING & TECHNOL

Ch. 1 - What is the difference between an atom and a...Ch. 1 - Prob. 2RQ Ch. 1 - Prob. 3RQ Ch. 1 - Prob. 4RQ Ch. 1 - Define anisotropy. What is its significance?Ch. 1 - What effects does recrystallization have on the...Ch. 1 - What is strain hardening, and what effects does it...Ch. 1 - Explain what is meant by structure-sensitive and...Ch. 1 - Prob. 9RQ Ch. 1 - What influence does grain size have on the...

Ch. 1 - What is the relationship between the nucleation...Ch. 1 - What is a slip system, and what is its...Ch. 1 - Explain the difference between recovery and...Ch. 1 - What is hot shortness, and what is its...Ch. 1 - Explain the advantages and limitations of cold,...Ch. 1 - Describe what the orange peel effect is. Explain...Ch. 1 - Some metals, such as lead, do not become stronger...Ch. 1 - Describe the difference between preferred...Ch. 1 - Differentiate between stress relaxation and stress...Ch. 1 - What is twinning? How does it differ from slip?Ch. 1 - Prob. 21QLP Ch. 1 - What is the significance of the fact that some...Ch. 1 - Is it possible for two pieces of the same metal to...Ch. 1 - Prob. 24QLP Ch. 1 - A cold-worked piece of metal has been...Ch. 1 - What materials and structures can you think of...Ch. 1 - Two parts have been made of the same material, but...Ch. 1 - Do you think it might be important to know whether...Ch. 1 - Explain why the strength of a polycrystalline...Ch. 1 - Describe the technique you would use to reduce the...Ch. 1 - What is the significance of the fact that such...Ch. 1 - Prob. 32QLP Ch. 1 - It has been noted that the more a metal has been...Ch. 1 - Is it possible to cold work a metal at...Ch. 1 - Comment on your observations regarding Fig. 1.14.Ch. 1 - Is it possible for a metal to be completely...Ch. 1 - Prob. 37QTP Ch. 1 - Prob. 38QTP Ch. 1 - Plot the data given in Table 1.1 in terms of...Ch. 1 - A strip of metal is reduced from 30 mm in...Ch. 1 - Prob. 41QTP Ch. 1 - How many grains are there on the surface of the...Ch. 1 - Prob. 43QTP Ch. 1 - Prob. 44QTP Ch. 1 - Prob. 45QTP Ch. 1 - A technician determines that the grain size of a...Ch. 1 - If the diameter of the aluminum atom is 0.28 nm,...Ch. 1 - The following data are obtained in tension tests...Ch. 1 - Prob. 50QTP Ch. 1 - Prob. 51QTP Ch. 1 - Prob. 52QTP Ch. 1 - Same as Prob. 1.39, but ASTM no. versus...Ch. 1 - By stretching a thin strip of polished metal, as...Ch. 1 - Draw some analogies to mechanical fiberingfor...Ch. 1 - Draw some analogies to the phenomenon of hot...Ch. 1 - Take a deck of playing cards, place a rubber band...Ch. 1 - Give examples in which anisotropy is scale...Ch. 1 - The movement of an edge dislocation was described...

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