Nanomateriales #1
Enviado por Eduardo González • 1 de Julio de 2023 • Apuntes • 620 Palabras (3 Páginas) • 18 Visitas
1.- A FCC Cu single crystal is subjected to a uniaxial load along the [112] direction. What is/are the first slip systems? If CRSS is 50 MPa, what is the tensile stress at which Cu will start to deform plastically?
Slip plane (n) | Slip direction (s) | [pic 1] | [pic 2] | [pic 3] | [pic 4] |
[pic 5] | [pic 6] [pic 7] [pic 8] | [pic 9] | [pic 10] [pic 11] 0 | [pic 12] [pic 13] 0 | 184 184 ? |
[pic 14] | [pic 15] [pic 16] [pic 17] | [pic 18] | [pic 19] [pic 20] [pic 21] | [pic 22] [pic 23] [pic 24] | 367 -122 184 |
[pic 25] | [pic 26] [pic 27] [pic 28] | [pic 29] | [pic 30] [pic 31] [pic 32] | [pic 33] [pic 34] [pic 35] | 122 -367 184 |
[pic 36] | [pic 37] [pic 38] [pic 39] | [pic 40] | [pic 41] [pic 42] 0 | 0 0 0 | ? ? ? |
The smallest stress magnitudes to cause slip (Yielding) in are -122 and 122 mPa, respectively.[pic 43]
Therefore, the first slip systems (Plane, direction) are then [pic 44]
2.- Sketch the following directions in a cubic unit cell:
[pic 45]
[pic 46]
[pic 47]
3.- Aluminium foil for storing food weighs around . How many Al atoms does one square inch of foil have?[pic 48]
.[pic 49]
4.- An attempt is made to produce an alloy with a yield stress of 3000 psi. Tests performed show, that a grain size of 5 μm gives a resistance of 4000 psi and that a grain size of 100 μm gives a resistance of 1200 psi. Find the alloy optimal grain size.
Using the hall-petch equation:
[pic 50]
Where σy is the yields stress, σ0 is a materials constant for the starting stress for dislocation movement (or the resistance of the lattice to dislocation motion), ky is a materials constant for the starting stress for dislocation movement (or the resistance of the lattice to dislocation motion), and d is the average grain diameter.
For 5 μm:
[pic 51]
For 100 μm:
[pic 52]
Then we make an equivalence:
[pic 53]
[pic 54]
[pic 55]
K is replaced to obtain :[pic 56]
[pic 57]
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