This composite material offers characteristics of both materials - the hardness and abrasion resistance of silicon carbide with the stress absorbing character of the embedded carbon fibers. The first edition was based on a balanced treatment of the full spectrum of engineering materials.
New to this Edition
Powers of Ten.” In Chapter 1, we point out that a fundamental principle of materials science is that understanding the behavior of materials in engineering designs (at the human scale) is achieved by looking at mechanisms that occur at various fine scales, such as the atomic-scale diffusion of carbon atoms involved in the heat treatment of steel. Much of modern engineering practice has depended on engineering designs based on micrometer-scale structures such as transistors in an integrated circuit.
Supplementary Material
Since the debut of the first edition, we have also seen advances in materials characterization, such as the evolution of high-resolution transmission electron microscopy (HRTEM), and in materials processing, such as additive manufacturing (AM). An important addition to IRC is a complete set of all figures and tables from the textbook in PowerPoint® format.
Acknowledgments
This set of slides was created by the University of California, Davis Extension in conjunction with an online course based on this book and can be very helpful to teachers as they prepare their own lectures. University; Yu-Lin Shen, University of New Mexico; Qiuming Wei, University of North Carolina at Charlotte; Blair Polytechnic State University, London, California; James Chelikowsky, University of Texas at Austin.
About the Author
Chapter 1
- The Material World
- Materials Science and Engineering 1.3 Six Materials That Changed Your World
- Materials Science and Engineering
- Six Materials That Changed Your World
First, Al2O3 is chemically stable in a broad Figure 1.2 The Golden Gate Bridge north of San Francisco, California, is one of the most famous and beautiful examples of a steel bridge. Secondly, the ceramic Al2O3 has a significantly higher melting point (2020 °C) than the metallic Al (660 °C), making Al2O3 a popular refractory material (i.e. a high temperature resistant material widely used in industrial furnace construction).
Structure Leads to Properties
Processing and Selecting Materials
Second, and most importantly, it provides an estimate of the effects of processing history on properties. The rectangular shape in the middle of the micrograph is a metal component approximately 32 nm wide.
Looking at Materials by Powers of Ten
The wide variety of materials available to engineers can be divided into six categories: metals, ceramics, glass, polymers, composites, and semiconductors. Once we understand the properties of materials, we can process and select the appropriate material for a given application.
Summary
The human scale and atomic scale are practical endpoints above and below the three SI scales. Understanding the properties of these different materials on a human scale requires the study of structure at some fine scale.
Key Terms
For Chapter 1, the references are some general materials science and engineering textbooks. Rethwisch, Materials Science and Engineering—An Introduction, 8th ed., John Wiley & Sons, Inc., New York, 2009.
- ChaPter 2 atomic Bonding
- ChaPter 3 Crystalline Structure— Perfection
- ChaPter 4 Crystal Defects and Noncrystalline Structure— Imperfection
- ChaPter 5 Diffusion
- ChaPter 6 Mechanical Behavior
- ChaPter 7 thermal Behavior
- ChaPter 8 Failure analysis and Prevention
- ChaPter 9 Phase Diagrams— equilibrium Microstructural Development
- ChaPter 10 Kinetics— heat treatment
- atomic Structure
- atomic Structure 2.2 the Ionic Bond
- the Secondary, or van der Waals, Bond 2.6 Materials— the Bonding Classification
Each of the five fundamental types of engineering materials (metals, ceramics, glasses, polymers and semiconductors) is associated with a certain type (or types) of atomic bonding. In general, the number of protons in the nucleus is known as the element's atomic number.
Naming a New Chemical element
1, shown in Figure 2.6, shows that the Coulombic force of attraction increases dramatically as the distance between adjacent ion centers (a) decreases. In this way, the net binding force curve shown in Figure 2.7 is a derivative of the binding energy curve.
The bond force and bond energy curves for covalent bonding look similar to those shown in Figure 2.8 for ionic bonding. Nevertheless, the general terminology of bond energy and bond length applies in both cases (Figure 2.18).
Discuss this structure in light of the prediction from Table 2.1 that non-directional bonding of spheres of equal size should have a coordination number of 12. From Linus Pauling, The Nature of the Chemical Bond and the Structure of Molecules and Crystals;.
But when another argon atom comes close, the negative charge is slightly pulled towards the positive nucleus of the neighboring atom. Since the degree of charge distortion associated with the induced dipole is small, the magnitude of the resulting dipole is small, leading to a relatively small bond energy (0.99 kJ>mol or 0.24 kcal>mol). Due to the directional nature of electron sharing in covalent O¬H bonds, H atoms become positive centers and O atoms become negative centers for H2O molecules.
Note that one of the important properties of water originates from the hydrogen bond. This bond energy is less than 1% of the size of any of the primary (covalent) bonds listed in Table 2.2.
Materials— the Bonding Classification
While the chemical identity of each atom is determined by the number of protons and neutrons within its nucleus, the nature of atomic bonding is determined by the behavior of the electrons orbiting the nucleus. Second, covalent bonding involves the sharing of electrons and is highly directional, which can lead to relatively low coordination numbers and more open atomic structures. In the absence of electron transfer or sharing, a weaker form of bonding is possible.
The classification of engineering materials recognizes a specific bond type or combination of types for each category. Composites are a sixth category and represent combinations of the first four basic types and have bonding properties appropriate to their constituents.
Key terms
Ceramics and glasses involve ionic bonding, but usually in conjunction with a strong covalent character. Polymers typically involve strong covalent bonds along polymeric chains, but have a weaker secondary bond between adjacent chains.
Problems
Chapter 3
- Seven Systems and Fourteen Lattices
- Seven Systems and Fourteen Lattices 3.2 Metal Structures
- Ceramic Structures 3.4 Polymeric Structures
- Lattice Positions, Directions, and Planes 3.7 X-Ray Diffraction
The length of the edges of the unit cell and the angles between the crystallographic axes are called lattice constants or lattice parameters. A key feature of the unit cell is that it contains a complete description of the structure as a whole, because the entire structure can be created by repeatedly stacking adjacent unit cells facing each other throughout three-dimensional space. First, there are only seven unique shapes of unit cells that can be stacked together to fill three-dimensional space.
Second, we need to consider how atoms (viewed as hard spheres) can stack together within a given unit cell. The lattice parameters a, b, and g are angles between adjacent unit cell axes, where a is the angle seen along the a axis (ie, the angle between the b and c axes).
Crystal (Bravais) Lattices
- Metal Structures
- Ceramic Structures
- Polymeric Structures
- Semiconductor Structures
The hexagonal close-packed (hcp) structure (Figure 3.6) is our first encounter with a structure more complicated than the Bravais lattice (hexagonal). In contrast, the structure of sodium chloride (NaCl) shown in Figure 3-9 is shared by many important ceramic materials. Close inspection of the structure shown in Figure 3.17(a) indicates that the nearly spherical molecule is in fact a polyhedron composed of 5- and 6-sided faces.
As illustrated in Figure 3.18, graphene is simply a single atomic layer of graphite (compare Figure 3.16). The elemental semiconductors (Si, Ge and gray Sn) share the cubic structure of diamond shown in Figure 3.20.
Growing a (Nearly) Perfect Crystal
Lattice Positions, Directions, and Planes
For example, the body-centered position in the unit cell protrudes midway along each of the three unit cell edges and is designated the 121212 position. Which lattice points lie in the [110] direction in the unit cells fcc and fco in table 3.2. Calculate the planar density of atoms in the (111) plane of (a) bcc tungsten and (b) fcc aluminum.
A close look at Figure 3.20 shows that the four inner atoms in the diamond cubic structure do not lie on the (111) plane. Calculate the planar density of atoms in the (111) plane of (a) bcc iron and (b) fcc nickel.
X-Ray Diffraction
Use Bragg's law and calculate the diffraction angles (2u) for the first three peaks in the aluminum powder pattern of Figure 3.33. List the lattice point positions for the corners of the unit cell in (a) the base-centered orthorhombic lattice and (b) the triclinic lattice. List the members of the family of prismatic planes for the hexagonal unit cell 501106 (see Figure 3.27).
List the members of the 81009 family for (a) the tetragonal system and (b) the orthorhombic system. List the members of the {100} family for (a) the tetragonal system, and (b) the orthorhombic system. a) List the first three lattice points (including the 000 point) that lie on the [112] direction in the fcc lattice.
Chapter 4
- The Solid Solution— Chemical Imperfection
- Point Defects— Zero- Dimensional Imperfections
- Linear Defects, or Dislocations—
One- Dimensional Imperfections 4.4 Planar Defects— Two- Dimensional
Imperfections
- Noncrystalline Solids— Three- Dimensional Imperfections
- Linear Defects, or Dislocations— One- Dimensional Imperfections
- Planar Defects— Two- Dimensional Imperfections
- Noncrystalline Solids— Three- Dimensional Imperfections
Such an interstitial solid solution is shown in Figure 4.4, which shows carbon dissolved in the interstitium in a-Fe. In other words, all the Ni2+ ions in Figure 4.5 could not be indiscriminately replaced by Al3+ ions. In a perfect crystal [Figure 4.11(a)], the m * n atomic step-loop closes at the initial point.
The grain boundary structure in this general case is considerably more complex than that shown in Figure 4.18. With atomic structure in mind, we can return to the microstructural view of grain structures (eg Figure 4.17).
Electron Microscopy
Chapter 5 Diffusion
- Thermally Activated Processes
- Thermally Activated Processes 5.2 Thermal Production of Point Defects
- Alternate Diffusion Paths
- Thermal Production of Point Defects
- Point Defects and Solid-State Diffusion
- Steady-State Diffusion
To understand why the rate data show the characteristic behavior of Figure 5.1, we need to explore the concept of activation energy, Q. A great strength of this analysis is that the result (Eq. 5.11) allows all the concentration profiles in Figure 5.10 to be replotted onto a single master plot (Figure 5.11). For the void mechanism, void formation is an integral part of the diffusion process (see Figure 5.5) and q = Edefect + Edefect motion.
The change in concentration profile with time for processes such as carburization is shown in Figure 5.10. Similarly, both ch and cl are kept fixed in the case shown by Figure 5.15.
Diffusion in Fuel Cells
Chapter 6
- Stress Versus Strain 6.2 Elastic Deformation
- Creep and Stress Relaxation 6.6 Viscoelastic Deformation
- Stress Versus Strain
- Elastic Deformation
- Plastic Deformation
- Hardness
The values of four of the five basic tensile test parameters (defined in Figure 6.6) for various alloys are given in Table 6.1. The general appearance of the stress versus strain curve in Figure 6.3 is typical of a wide variety of metal alloys. Figure 6.17 also shows the difference in the modulus of elasticity (slope of the surface near the origin) for tensile and compressive loading. (Recall that this point was raised when the flexural modulus was introduced.) Table 6.6 shows the mechanical properties of thermoplastic polymers (those that become soft and deformable when heated).
In fact, cold work creates so many dislocations that the configuration is called a "forest of dislocations" (Figure 6.25). The hardness test (Figure 6.28) is offered as a relatively simple alternative to the tensile test of Figure 6.1.
