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| It is possible for a given material to exhibit properties attributable to both covalent bonding and metallic bonding modes. |
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Definition
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| Stable bonding between atoms occurs when the energy of the bonded state is higher than the energy of the unbonded (non-interactive) state. |
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| Almost without exception, the independent variable in a Charpy v-notch impact test on a given alloy is the test temperature. |
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Definition
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| The general trend with metals is that the higher the melting point of the metal, the lower is the thermal expansion coefficient of the metal. |
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Definition
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| The data from a creep test would provide useful design information for the selection of steel to be used for structural members of a highway bridge. |
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Definition
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| The structure intensive properties of a metal sample are virtually material constants, and vary very little with teh prior thermal and/or mechanical history of the metal sample. |
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Definition
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| The thermal expansion coefficients of polymers as a group tend to be much higher in value than the thermal expansion coefficients of metals as a group. |
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Definition
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Term
| An atom having a ground-state electron configuration of 1s^22s^22p^23s^23p^2 would be correctly clasified as "non-metal." |
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Definition
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| Domains are regions in ferromagnetic materials in which the net magnetic moments of all the atoms are aligned in the same direction. |
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Definition
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Term
| Hydrogen bonds result from a weak coulombic interaction between molecules having permanent dipole moments. |
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Definition
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Term
| Elastic strain in a metal corresponds to the stretching of interatomic bonds and is fully recoverable on removal of the load. |
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Definition
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Term
| The BHmax. product is a measure of the maximum stored elastic strain energy in an elastically deformed ferromagnetic material. |
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Definition
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Term
| Escellent electrical and thermal conductivities are characteric of materials containing "free", or mobile valence electrons. |
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Definition
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Term
| Face-centered cubic metals and alloys (Al, brass, austenitic stainless steel) retain their toughness even at very low (cryogenic) temperatures. |
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Definition
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Term
| Necking is form of heterogeneous or lcalized, plastic deformation that occurs during the tensile testing of ductile metals and alloys. |
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Definition
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Term
| Surface conditions, such as smoothness and state of residual stress, can have a significant effect on the fatigue properties of an engineering structure or component. |
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Definition
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Term
| The hardness tests discussed in this course generally employ some type of indenter which is slowly forced into the test material under a given load. |
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Definition
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Term
| The electrical conductivity of molten salt (NaCl) is much improved over that of solid crystalline NaCl because the charge carriers are more mobile. |
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Definition
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Term
| The principal quantum number, n, indicates the major energy level, or shell, to shich an electron belongs. |
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Definition
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| Considering electronegative elements as a group, the ionic radius of the element is smaller than its respective atomic radius. |
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Definition
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Term
| Excellent electrical conductivity and excellent thermal conductivity are characteristic of materials containing free or mobile electrons. |
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Definition
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Term
| The creep test and the stress-rupture test are considered for most engineering materials to be elevated temperature mechanical tests. |
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Definition
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Term
| So-called permanent magnets can be fabricated only from ferromagnetic atoms, but cannot be fabricated from corresponding ions. |
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Definition
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Term
| Most commercial glass compositions are based on SiO2 with metal oxides additions to control virtually all other properties. |
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Definition
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Term
| The Charpy V-notch impact test measures the stress required to fracture a standard-sized test bar of the material of interest. |
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Definition
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Term
| Microhardness tests employ much lower testing loads than do the more common hardness tests. |
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Definition
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Term
| Van der Waals forces arise from a weak coulombic interaction between molecules having temporary or fluctuating dipole moments. |
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Definition
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Term
| The structure insensitive properties of a given material may vary by a few percent in value but they never vary by orders of magnitude. |
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Definition
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Term
| The Charpy V-notch impact toughness of a structural steel is more temperature-dependent than the impact toughness of face-centered cubic alloys such as aluminum and brass. |
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Definition
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Term
| Both the face-centered cubic and the hexagonal close-packed hard-sphere models may be visualized as an ordered stacking of planes of close-packed spheres. |
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Definition
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Term
| Cleavage fractures are associated with the brittle behavior of steel at low temperatures and they absorb very little energy during propagation. |
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Definition
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Term
| The mechanism of elastic deformation of a metal involves the stretching of interatomic bonds and is fully recoverable on removal of the load. |
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Definition
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Term
| Fatigue failure occurs only in componenets fabricated from metals but never in componenets frabricated from polymers or ceramics. |
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Definition
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Term
| The three quantum numbers n,l, and m designate the energy level of an electron in an atom the fourth quantum number s indicates the spin characteristics of the electron. |
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Definition
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Term
| An element having an electron configuration 1s2 2s2 2p6 3s1 would be correctly classified as a p-block element. |
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Definition
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Term
| Necking is a form of homogeneus plastic deformation that is commonly observed during tensile testing of brittle materials. |
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Definition
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Term
| Stainless steels are a group of ferrous alloys that have Cr (chromium) additions and are noted for their outstanding corrosion resistance. |
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Definition
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Term
| Ceramics are crystalline solids that typically contain both metallic and nonmetallic elements in the form of ions. |
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Definition
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| Typically, high melting points metals tend to have smaller thermal expansion coefficients than do metals having a low melting point. |
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| The buckyball was discovered by Buckminster Fuller. |
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