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Material Exam2
Words to know for Materials Engineering
Question | Answer |
---|---|
Modulus | Stiffness; resistance to elastic deformation. |
Strength | Resistance to plastic deformation. |
Hardness | Resistance to localized plastic deformation. |
Toughness | Resistance to fracture. |
Elongation | Extent of ductility...strain to fracture. |
Fatigue Resistance | Resistance to failure by damage accumulation. |
Elastic Deformation | Material reverts back to original shape and size after removal of loads. -Caused by separation of atoms. |
Plastic Deformation | Application and removal of load results in permanent change in shape/size. -Caused by defect or molecular motion. |
Linear Densisty | Number of atoms centered on a direction vector/length of the vector. |
Planar Density | Number of atoms centered on a plane/area of the plane. |
Ionic Bond | Low and High electro-negativity. |
Covalent Bond | 2 or more atoms of high electro-negativity. |
Metallic Bond | Metals; low electro-negativity of both. |
Crystalline Defect | Lattice irregularity having one or more dimensions on the order of an atomic diameter. |
Point Defects | Affect chemical and electrical properties, as well as determining phases for a given composition. |
Line defects | responsible for plastic deformation and lower than theoretical strength. |
Planar Defects | Defines internal and external boundaries that affect strength, diffusion, and shape. |
Volume Defects | Can harden material by interacting with other defects...or lead to failure. |
Vacancies | Absense of atoms |
Interstitials | Atoms of elements different than those comprising the basis for the lattice. |
Self-Interstitual | "extra" atom positioned between atomic sites. |
The number of Vacancies... | Increases Rapidly with Temperature. |
Vacancies Occur | -Upon Solidification -Due to atomic vibrations -By radiation damage |
Frankel Defect | A cation vacancy - cation interstitial pair. |
Shottky Defect | A paired set of cation and anion vacancies |
Edge Dislocation | Displacement is perpendicular to axis. |
Burger's Vector | measure of lattice distortion. |
Screw Dislocation | Displacement is parallel to Axis. |
Grain Boundaries | Regions between crystals transition from lattice of one region to that of the other. |
Stacking Fault | A stacking fault is a misregistry in the stacking sequence. |
Interdiffusion | in a allow, atoms tend to migrate from regions of high concentration, to regions of low concentrations. |
Diffusion | Process of mass transport that involves the movement of one atomic species into another. |
Assumption | Occurs by random atomic jumps from one position to another. |
Why are jumps more frequent in higher temperatures? | Because of the higher thermal energy of the atoms, so the diffusion rate is more rapid. |
Vacancy Diffusions | Atoms exchange with vacancies; applies to substitution impurities atom. Rate depends on: Number of Vacancies; activation energy exchange. |
Interstitial Diffusion | Smaller atoms can diffuse between atoms. *More rapid then vacancy diffusion. |
Case Hardening | Diffuse carbon atoms into the host iron atoms at the surface. |