X
Courses » Defects in Crystalline Solids (Part-I)
Unit 8 - Week 6
Announcements Course Ask a Question Progress Mentor FAQ
Course outline
How to access the portal Week 1 Week 2 Week 3 Week 4
DOWNLOAD VIDEOS Week 5
Week 6 Lecture 26:
Resistance to Dislocation Motion+Peierl Nebarro Valley Lecture 27: Slip System+Examples Lecture 28:
Dislocations and
Slips+Examples Lecture 29:
Critical resolved Shear Stress+Examples Contd...
Lecture 30:
Glide+Kinks Quiz : Assignment 6 WEEK 6 - FEEDBACK - Defects in Crystalline
Due on 2018-09-19, 23:59 IST.
1) 1 point
2) 1 point
3) 1 point
Assignment 6
The due date for submitting this assignment has passed.
As per our records you have not submitted this assignment.
Which of the following is true for FCC system
P. Number of atoms per unit area on (111) plane is 4/[(√3)(a2)]
Q. Distance between (111) planes is ao /√3
R. {111} planes have the smallest interplanar distance and lowest planar density of atoms
Only Q is true Only Q and R are true Only P and Q are true All of P, Q and R are true No, the answer is incorrect.
Score: 0
Accepted Answers:
Only P and Q are true
Which of the following are true for BCC systems
P. Number of atoms per unit area on (111) plane is 1/(ao2) Q. Distance between (111) planes is ao /√3
R. {111} planes have the highest planar density of atoms with largest interplanar spacing
Only Q is true Only Q and R are true Only P and Q are true None of P, Q and R are true No, the answer is incorrect.
Score: 0
Accepted Answers:
None of P, Q and R are true
Which one of the following represents the slip system for FCC materials?
{111}<110>
{112}<110>
{001}<123>
A project of In association with
Funded by
© 2014 NPTEL - Privacy & Terms - Honor Code - FAQs -
Powered by
Week 7 Week 8 Lecture Notes
Solids (Part-I) Assignment 6 Solution
4) 1 point
5) 1 point
6) 1 point
{010}<010>
No, the answer is incorrect.
Score: 0
Accepted Answers:
{111}<110>
Which one of the following represents the slip system for BCC materials?
{110}<111>
{112}<110>
{001}<123>
{010}<010>
No, the answer is incorrect.
Score: 0
Accepted Answers:
{110}<111>
If it is given that a single crystal starts to yield at a stress σy along a particular slip system, then which of the following relation represents the Schmid’s law?(here, λ is the angle between the direction of applied stress and the burger vector, while φ is the angle between the slip-plane normal and the direction of applied stress)
t
CRSS = ±(σy)Cos2λCosφt
CRSS = ±(σy)CosλCosφt
CRSS = ±(σy)CosλCos2φt
CRSS = ±(σy)2CosλCosφ No, the answer is incorrect.Score: 0
Accepted Answers:
t
CRSS = ±(σy)CosλCosφConsider a thin cylindrical metal whisker and find the maximum thickness of the shell of the whisker which may be free of dislocations. (You may take the values of G= 400 GPa, b = 4 Å, ν= 0.5, and assume that a min F/L=1.02 N/m is required for dislocations to move. You can additionally assume that the glide planes are horizontal/radial w.r.t. the whiskers)
7) 1 point
8) 1 point
9.9 nm 99 nm 45 nm 4.5 nm
No, the answer is incorrect.
Score: 0
Accepted Answers:
9.9 nm
Which of the following statement is NOT true for critical resolved shear stress (CRSS)?
CRSS is the resolved shear stress at which yielding begins inside a crystal, marking the onset of plastic deformation
CRSS is a material property CRSS depends on the applied load
CRSS does not depend on the crystal orientati No, the answer is incorrect.
Score: 0
Accepted Answers:
CRSS depends on the applied load
A tensile stress of σ = 4 KPa is applied parallel to the [4 3 2] direction of a cubic crystal.
Calculate the resolved shear stress on the (I I I) plane in the [0 I I] direction?
6.34 KPa 180 KPa 2.53 KPa 0.089 KPa
No, the answer is incorrect.
9) 1 point
10) 1 point
Score: 0
Accepted Answers:
2.53 KPa
Calculate the tensile stress that is applied along the [I Ī 0] axis of a copper crystal to cause slip on [I Ī Ī](0 Ī I). It is given that the critical resolved shear stress is 10 MPa?
24.5 MPa 4.1 MPa 5.0 MPa 20.0 MPa
No, the answer is incorrect.
Score: 0
Accepted Answers:
24.5 MPa
If an edge dislocation moves in the direction given below in the figure and forms a jog, then what is the nature of dislocation of the various sections of the jog (L1, L2 and L3)? (Assume that all steps are at right angles to each other)
L1: Screw dislocation; L2: Edge dislocation; L3: Screw dislocation L1: Edge dislocation; L2: Edge dislocation; L3: Edge dislocation L1: Screw dislocation; L2: Screw dislocation; L3: Screw dislocation L1: Edge dislocation; L2: Screw dislocation; L3: Edge dislocation No, the answer is incorrect.
Score: 0
Accepted Answers:
L1: Screw dislocation; L2: Edge dislocation; L3: Screw dislocation
