Term
What are the hkl conditions for different lattice types for diffraction |
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Definition
P cubic- none I - h+k+l = 2n C - h+k = 2n F h,k,l all odd or all even |
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Term
What are the characteristics (lattice parameter restrictions, angle restriction, characteristic symmetry) of the seven crystal systems? |
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Definition
Triclinic a1 not= a2 not= a3; alpha not= beta not= gamma; monad symmetry monoclinic a1 not = a2 not= a3; alpha = gamma beta>= 90; 1 diad orthorhombic a1 not= a2 not=a3; alpha= beta= gamma = 90; 3 diads tetragonal a1 = a2 not= a3; alpha= beta= gamma = 90; 1 tetrad trigonal a1 = a2 = a3; alpha = beta = gamma not= 90; 1 triad hexagonal a1 = a2 not= a3; alpha = beta = 90 gamma = 120; 1 hexad cubic a1=a2=a3; alpha= beta= gamma= 90;; 4 triads |
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Term
What are the 14 bravais lattices? |
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Definition
Triclinic P; Monoclinic P&C; Orthorhombic P,C, I&F; Tetragonal P&I, Hexagonal, Trigonal P; Cubic P,F &I |
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Term
What are the 14 bravais lattices? |
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Definition
Triclinic P; Monoclinic P&C; Orthorhombic P,C, I&F; Tetragonal P&I, Hexagonal, Trigonal P; Cubic P,F &I |
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Term
What is Weiss zone rule? How do you prove it? |
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Definition
If a direction [uvw] is contained in a plane (hkl) then the normal to the plane is perpendicular to the direction: (ha*+kb*+lc*)(ua+vb+wc) = 0 a*a = 1, b*b = 1, c*c=1 hu + kv+ lw = 0 (weiss zone rule) |
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Term
Which Bravais lattices have a centre of symmetry? |
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Definition
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Term
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Definition
the collection of symmetry operations passing through a point. |
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Term
What does m represent? What do bars on top of rotation axes represent? 2/m? mm2? how else can you write mm2? What does the first number represent? What's the exception to the rule stated earlier |
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Definition
m - mirror; bars- inversion axes; 2/m- mirror plane perpendicular to a diad axes; mm2- two mirror planes intersecting at a two-fold axis- can also be written as mm or 2m; the first number always refers to a c-axis except in the monoclinic system where the b axis is unique. |
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Term
In a cubic crystal/stereogram, which planes have triad symmetry? tetrad symmetry? diad symmtery? |
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Definition
triad- {111} tetrad- {100} diad- {100} and {110} |
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Term
What is the requirement for a crystal to be piezoelectric? |
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Definition
Must lack a centre of symmetry |
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Term
What are polar point groups? |
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Definition
point groups that have a unique direction which is not related by the symmetry elements to any other |
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Term
In the hkil notation used for hexagonal crystal systems, what is the relationship between i and h, k, and l? |
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Definition
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Term
What is a diagonal glide plane and what is its symbol? |
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Definition
the translations involve two orthogonal steps parallel to a face of the unit cell. It's symbol is n. |
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Term
What are the different types of glides? there symbols and characteristics? |
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Definition
An axial glide is parallel to one of the lattice vectors and has the symbol of the axis it's parallel to. A diagonal glide is parallel to a face diagonal and has the symbol n. A diamond glide (f.c.c) is parallel to the face diagonal and has the symbol d. A diamond glide (b.c.c) is parallel to the body diagonal and has the symbol d. |
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Term
explain the statement k'-k = g. |
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Definition
This is another way of stating Bragg's law. k and k' have magnitudes of 1/lambda and g has a magnitude of 1/d. |
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Term
how are Intensity and structure factor related? |
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Definition
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Term
What's the Schmidt factor? |
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Definition
cos(theta)cos(lambda); gives the shear on a slip plane in the slip direction. Slip occurs when Schmidt factor reaches a maximum |
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Term
How do you tell which slip direction, you have slip along using stereographic projection? (Diehl's rule) |
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Definition
1) Identify the triangle containing the tensile axis 2) to find slip plane take {111} type pole and reflect across opposite side 3)to find the slip direction take the <110> type pole and reflect across the opposite side 4) this is for ccp crystals do opposite for bcc crystals; rather reflecting the <111> type pole will give you the direction etc. 5) tensile axis moves towards slip direction 6) once tensile direction reaches triangle side changes slip system |
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Term
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Definition
a stereogram with its axes defined relative to the external frame of reference , and with particular hkl poles from each of the crystals in the polycrystalline aggregate plotted on it. |
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Term
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Definition
pole figure in which the sample frame is plotted relative to the crystal axes of a reference crystal. |
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Term
How is crystallographic texture measured? |
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Definition
using a variety of techniques such as X-ray diffraction, EBSD |
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Term
What are some disadvantages of pole figures? Give an alternative method and define it. |
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Definition
They do not give information about the orientation of a particular crystal relative to another, since the poles are not identified with particular crystals in the final plot. Use an orientation distribution function which plots the euler angles |
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Term
Why does the the interfacial energy pf a tilt boundary as a function of misorientation angle not consistently rise with increasing theta? |
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Definition
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Term
What is the General Rotation Matrix given a vector unit vector u = [u1 u2 u3] and an angle of rotation theta? |
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Definition
let m = cos theta and n = sin theta u1u1(1-m)+m u1u2(1-m)+u3n u1u3(1-m)-u2n u1u2(1-m)-u3n u2u2(1-m)+m u2u3(1-m)+u1n u1u3(1-m)+u2n u2u3(1-m)-u1n u3u3(1-m)+m |
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Term
How can you find the angle of rotation for an axis of rotation if you are given the general rotation matrix J? |
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Definition
J11+J22+j33 = 1+2cos(theta) |
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Term
What is the meaning of Epsilon in CSL notation? |
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Definition
1/epsilon is the number of lattice sites common to both crystals out of the numbe rof total lattice point. |
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Term
What is Bain strain? What are the two inconsistencies associated with Bain strain? |
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Definition
The strain necessary to transformf.cc austenite into b.cc martensite. you would expect the |
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