问题 问答题

如图所示,某晶体的滑移面上有一个柏式矢量为b的位错环,并受到一个均匀的切应力τ的作用,试分析:

1.该位错环各段位错的结构类型。

2.求各段位错所受力的大小和方向。

3.在τ的作用下,该位错环将要如何运动。

4.在τ的作用下,若该位错环在晶体中稳定不动,其最小半径应该是多大?

答案

参考答案:

1.A为正刃型位错,B为右螺旋位错,C为负刃型位错,D为左螺旋位错,其他为混合型位错。

2.各段位错所受的力大小均为τb,方向垂直于位错线指向环外。

3.在外加切应力τ的作用下,位错环将向外扩散。

4.由公式,在τ的作用下,此位错环要稳定不动,其最小半径为rmin=

完形填空
Mary is __41__  English girl, but she is in France (法国) now. She is six __42__ old. Her mother says to her. “You are six,   43  you will be school here. You will like the school because (因为) it’s a __44__ school.” “Is it an English school?” Mary asks. “Yes, it  45  .” Mother answers.
Mary goes to school. The teachers __46__ very friendly and speak good __47__. And there   48  two other English girls in the class, __49__. She begins to like the school.
Her mother takes her  50  school __51__ the morning and brings her home in the afternoon.
One day ,when her mother is at school, Mary runs out  52   the classroom and says, “We have a __53__ girl in our class today. She is six, too. She is very nice, __54__ she isn’t English. She is a German (德国人).” “Doesn’t she speak English?” Mary’s mother asks. “No, but she always laughs __55__ English.” She says happily.
小题1:
A.anB.aC.theD./
小题2:
A.yearB.yearsC.years’D.year’s
小题3:
A.and B.but C.or D.at
小题4:
A.oldB.badC.smallD.nice
小题5:
A.isB.amC.areD.has
小题6:
A.areB.isC.aren’tD.isn’t
小题7:
A.JapaneseB.EnglishC.ChineseD.French(法语)
小题8:
A.isB.amC.areD.have
小题9:
A.eitherB.alsoC.allD.too
小题10:
A.toB.fromC.atD.in
小题11:
A.onB.atC.inD.of
小题12:
A.inB.onC.atD.of
小题13:
A.niceB.newC.goodD.old
小题14:
A.andB.orC.butD.because
小题15:
A.inB.atC.withD.on
单项选择题