试题与答案

弹性变形机理和弹性后效产生原因及其消除办法() A.当外力去除后,仍然保持一定的变形

题型:多项选择题

题目:

弹性变形机理和弹性后效产生原因及其消除办法()

A.当外力去除后,仍然保持一定的变形量

B.弹性变形是当外力去除后,能完全恢复的变形

C.弹性变形的机理是:在正常情况下,晶体内部原子所处的位置是原子间引力和斥力达到平衡时的位置。当有外力作用时,原子就会偏离原来的平衡位置,同时产生与外力方向相反的抗力,与之建立新的平衡。当外力去除后,为消除出现的新的不平衡,原子又恢复到原来的稳定位置

D.消除办法:消除弹性后效现象的办法是长时间回火,以使应力在短时间内彻底消除

答案:

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下面是错误答案,用来干扰机器的。

参考答案:C

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题型:单项选择题

阅读下面短文,回答问题
有记忆的金属
1963年,美国海军研究所在研究镍钛合金时,发现一种奇怪的现象:一些已经被拉直了的镍钛合金丝,无意中被火烘烤后,又恢复到原来的弯曲形状。这一现象说明这种镍钛合金具有一种形状记忆功能。所谓形状记忆功能,就是指合金能“记住”它在某一特定温度下的形态,以后不管经过什么样的温度变化,只要出现那一特定的温度,它便能立即恢复原来的形状。现在,世界各国已经研制出几十种具有“记忆”能力的合金。最具有代表性的是由51%的镍和49%的钛组成的镍钛合金。
那么,形状记忆合金的“记忆”奥秘何在呢原理是这样的:在一定的温度范围内,合金内部有一种特殊的可逆性结构变化。形状记忆合金受到很大的外力作用时,内部的金属原子可以暂时离开自己原来的位置,被迫迁到邻近的位置上,并暂时留在那个位置上。这时,我们可以看到形状记忆合金改变了它们的形状。如果把这变了形的合金加热(浇热水或用强光照射),那么,金属原子由于获得了运动所需的足够能量,同时在原结构合力的作用下,就又重新回到原来的位置上,合金便恢复了原来的形状。
1970年美国首先将形状记忆合金用于制作宇宙飞船天线,成为形状记忆合金应用的最杰出代表。在此之前,占用空间大、形状不规则的太空天线搭载一直是困扰航天界的一大难题。用形状记忆合金在较高温度下将天线压制成型,然后在低温下压制成致密形状。它随航天器发射到达太空后,由于阳光照射温度升高到成型温度,天线变形完全消失,并回复到变形前高温状态下的形状。经过压缩的新天线比原来的太空天线大大减小了运载空间,也不容易损坏,恢复原状后,自然可以“精神百倍”地投入工作了。
在医学上,形状记忆合金被制成金属片或夹钳,装在人造肢体的关节处,或用来压合严重破裂的碎骨及矫正弯曲的脊椎,有时也用作骨板和保持动脉畅通的内部支撑结构。其原理都是利用它的记忆功能,先在下把它加工成所需的形状,再在较低温度下将其制成便于植入人体的简单形状并送人人体指定部位,在人体内合金会自动恢复初始形状,实现矫正或支撑的功能。
在日常生活中,形状记忆合金大多被用来制作温度控制开关或电热驱动装置。煮咖啡的最佳温度是90摄氏度,利用形状记忆合金制作咖啡壶的温控开关,使他高于90度的时候自动断开,低于该温度时又自动接通。同样道理,形状记忆合金被广泛用于领域恒温器、自动干燥库、电磁炉、净水器等。英国一家公司研制的窗户弹簧开启器,白天气温高,它会自动打开窗户,晚上天气凉,它便自动关窗,可谓“体贴人微”。工业生产中,通过各种“形状记忆”元件的互相配合,可以实现各工序间甚至整个生产过程的自动控制。
(载《科学奇迹》,灵犀工作室编著,青岛出版社,2007.个别文字有改动)

根据文章对记忆合金原理的描述,下列对记忆合金应用的说法,不准确的是:

A.记忆合金可以用作温度控制开关、电热驱动装置等。

B.记忆合金制成的咖啡壶开关可以使咖啡温度维持在90摄氏度下。

C.用记忆合金制造的窗户弹簧开启器可以根据温度变化自动开关。

D.在工业生产中,各工序中所用到的记忆合金必须使用同一种材料,并在相同温度下制造。

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题型:阅读理解

阅读理解。

     More than 17,000 flights to and from European airspace were cancelled, including all flights from Britain's

major airports.

     The Met Office reported that volcanic ash had begun to fall across Britain, coating surfaces with a fine

layer of dust and raising fears for people with breathing difficulties.

     Meanwhile experts warned of shortages of some foods with produce destined for British shops rotting in

airport warehouses in other parts of the world.

     Geologists reported that activity at the volcano increased yesterday, spewing a plume of ash 5.3 miles high

into the atmosphere.

     The Icelandic Meteorological Office said the winds blowing the volcanic ash southeast to Europe and up

into Scandinavia and Russia will continue in the same direction for at least two days and could go on until

Wednesday. But scientists fear there could be more eruptions from the 5,466-foot volcano, Mount

Eyjafjallajkull. 

     A university geophysicist said, "From what we've seen, it could erupt, pause for a few weeks, and then

possibly erupt again. It could go on for months." As the no fly zone expanded yesterday, so did the chaos. 

The Icelandic volcano causing travel chaos across Europe could go on erupting for months, geologists have

warned.

     The National Air Traffic Control Service (Nats) extended restrictions on flights from British airports to

7 p.m. on Sunday, with the expectation of further extensions.

     Ferry operators have reported record bookings. P&O took 6,000 foot passengers across the Channel on

Friday compared to the 100 to 200 it would expect on a normal Friday in April.

     Eurostar trains were fully booked until tomorrow, with 50,000 more passengers than normal since the

airline disruption (中断) began on Thursday, including comedian John Cleese who arrived back in London last

night after a most difficult overland journey from Switzerland.

     The operator is charging passengers a minimum $223 for a single ticket from Paris to London over the

next two days prompting criticisms of profiteering. A return ticket can normally be bought for as little as 69.

Eurostar denied it was cashing in.

     Some 4,000 British tourists have been stranded in South Africa.

     The British Embassy in Athens said there were currently "many thousand" British holidaymakers trying to

leave Greece after the holidays, in many cases anxious to get back in time for the start of the school term this

week, with some of those desperate to return resorting to renting cars or embarking on long train journeys.

1. Where is the volcano, Mount Eyjafjallajkull located?

A. England

B. Ireland

C. Iceland

D. Switzerland

2. Which of the following is NOT the influence of the volcano eruption?

A. Breathing difficulties

B. Shortages of food

C. The airline disruption

D. A fine layer of sand

3. What does the underlined word "chaos" mean in Para. 6? 

A. Danger.

B. Anxiety.

C. Desperation.

D. Disorder.

4. From the passage, we know that the volcano eruption _____.

A. forced all the people to go back home

B. brought the train company a large profit

C. made 6,000 passengers take ships to cross the Channel

D. prevented British students from going to school on time

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