=========================preview======================
(CENG151)[2005](f)quiz1~jcychan^_10030.pdf
Back to CENG151 Login to download
======================================================
Quiz #1 of CENG 151
Introduction to Materials Science and Engineering
September 29, 2005 (Thursday)
LTG 12:00 - 1:20 pm
Name: Yongli Mi (Chinese) Solution (English)
Student ID Department
1.
Please name the following planes. When you are to move the origin, please indicate where the origin is. (10 points)
2.
Please group the plane family. (10 points)
1. 2. 3. (shift the origin up by 1) 4.
(100) (010) (111)
5. shift the origin 6. 7. 8.
(110) (101)
9. 10.
(011)
100 family: 1, 2, 3.
111 family: 4, 5, 6.
110 family: 7, 8, 9, 10.
3.
Please name the following directions. (10 points)
A B C D
4.
The following graph is the spectrum of x-ray diffraction for a FCC aluminium crystal, please answer the following: (30 points)
.
Why 111 is the strongest peak.
.
Please read the Figure caption and answer why it specifies that the sample needs to be in the powder form?
.
Can we just use one big piece of the aluminium single crystal to do the x-ray diffraction? What kind of diffraction pattern we would get if we used single crystal rather than the powdered sample?
.
For Figure 1, can we use the diffraction angle, , as the experimental variables instead of 2?
Figure 1 Diffraction pattern of aluminium powder. Each peak (in the plot of x-ray intensity versus diffraction angle, 2) represents diffraction of the x-ray beam by a set of parallel crystal planes (hkl) in various powder particles.
.
Because 11 plane has the highest packing density, the x-ray diffraction signal (intensity) is highest.
.
The sample in the powder form can ensure that all crystal planes will be exposed under the x-ray beam.
.
It will not be wise enough to use one big piece of the single crystal. If we use a piece of the single crystal, we will have only one crystal surface being exposed under the x-ray beam, so that we get only one diffraction peak in the x-ray diffraction spectrum.
.
2 is the experimental variable that we can precisely determine. is not the experimental variable since we could not determine its value experimentally Because the orientation of the individual particles cannot be determined, can only be determined indirectly.
5.
Referring to the last question, if the x-ray diffraction is carried out for a crystal which has the simple cubic packing pattern, do you think that the strongest diffraction peak will be 111? Please give enough reasons and support your argument with detailed analysis. (25 points)
In this case, the strongest diffraction peak is not 111. We can take a look of the planar packing density. The distance between any two adjacent atoms in (111) plane for simple cubic crystal is 1.414a, wh