作者weakhsuan (科科)
看板NTUMSE-98
標題[物冶] 第五次小考詳解
時間Fri Oct 29 09:53:48 2010
Physical Metallurgy Test 5 (October 28, 2010)
系級__________ 學號__________ 姓名__________
1.In early material studies, a discrepancy of many orders of magnitude existed
between the theoretical and observed yield stresses of crystals. Which model
can explain the observed low values of strength? How to explain. (10%)
dislocation
A few atoms move from low energy position on dislocation, no need of
all atoms on slip planes.
2.In an actual crystal, because of the more complex spatial arrangement of
atoms, the dislocations are complicated and often difficult to visualize.
However, two terms can be used to completely describe the dislocations.
Point out these two terms. (10%)
Burgers vector, dislocation line
3.The figure in Fig. 1 shows the orientation of a discolation line along the
direction of positive line sense. Is i a right-hand or left-hand screw
dislocation? Determine its Burgers vector according to the orientation of
the dislocation line. (20%)
left-hand, Burgers vector 略
4.The photograph in Fig. 2 shows a growth spiral on the surface of a crystal;
the crystal grows as a never-ending spiral. Can you indicate which type of
dislocation is associated with this typical spiral pattern? (20%)
screw dislocation
5.It has been well known that in FCC metal crystal, (111) planes are the
closest-packed planes and with the stacking sequence of ABCABC... If the
_
movement of an atom on B plane by a shear 1/2[110] relative to the
neighboring C plane, can this atom remain in the B stacking. Why?
Give your reason. (20%)
_
Yes, (1) 1×1－1×1＋0×1＝0 → 1/2[110] is on (111)
_
(2) 1/2[110] 也是FCC的最密方向, 滑移後仍然是B stacking.
shortest, lattice translation(左邊這個字我不確定= =) vector
6.Fig.3 plots the stereographic projection of a cubic crystal for the planes
of a zone with the zone axis [100]. Fig. 4 shows the electron diffraction
pattern corresponding to the electron beam directed along [100] in a cubic
crystal. By useing these two figures, make a brief comment on the
relationship between the reciprocal lattice and the electron diffraction
pattern. (20%)
l(011)/l(010)=d(010)/d(011)=(a/1)/(a/√2)=√2
(1) reciprocal lattice 的比例會和結晶面的間距成倒數關係
(2) electron diffraction pattern 的方向會和 standard projection的方向一樣
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這次詳解教授沒有提供
是助教影印Taddy的考卷然後他自己再加一些補充上去的
以上答案不代表本人立場
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◆ From: 111.240.3.164
1F：推 cj1234:推 10/29 19:57
2F：推 taddy441:為什麼是印我的??我都不知道 10/29 22:14
3F：→ taddy441:我來補充好了 第一題的中文不要管他(有些錯誤) 10/29 22:16
※ 編輯: weakhsuan 來自: 111.240.34.9 (10/29 22:22)
4F：→ weakhsuan:已修正 10/29 22:22